JPH0347813A - Acrylamide copolymer - Google Patents

Abstract

PURPOSE:To obtain the subject copolymer useful as a viscosity-increasing agent for paper-making or a coagulating dehydration agent and capable of improving the stringiness and water-solubility of an aqueous solution without increasing the viscosity by copolymerizing ammonium acrylate and other acrylic acid salt with acrylamide. CONSTITUTION:The objective copolymer having a viscosity of >=500cps measured by a Brookfield-type viscometer (12rpm, rotor #3, 25 deg.C) in the state of 1% aqueous solution is produced by copolymerizing acrylamide with other constituent monomers consisting of ammonium acrylate (abbreviated as ANH4) and acrylic acid salt other than ANH4. The acrylic acid salt other than ANH4 is preferably alkali metal salt such as sodium acrylate. Preferably, the total amount of the acrylic acid salts in the constituent monomers is 15-27mol% and the amount of ANH4 in the acrylic acid salts is 10-35mol%.

Description

Detailed Description of the Invention (a) Purpose of the Invention [Field of Industrial Application] The present invention provides a water-soluble acrylamide polymer with improved spinnability, a papermaking adhesive and a flocculating dewatering agent comprising the polymer. It is related to.

Due to its properties, water-soluble acrylamide polymers have a high degree of polymerization and give a highly viscous aqueous solution when dissolved in water, and are used as flocculating and dehydrating agents, sticky agents for papermaking, soil conditioners, thickeners, oil recovery agents, etc. It has been widely adopted and widely used in many industrial fields.

The acrylamide copolymer of the present invention is an improved version of the conventional water-soluble acrylamide polymer, and is used in the same manner as those polymers in the above-mentioned fields, and is particularly excellent as a sticky agent for paper making and a flocculating dehydrating agent. Due to its effectiveness, it can be used more widely in the paper industry and wastewater treatment industry.

[Prior Art] It is known that the performance of a water-soluble acrylamide polymer with a high degree of polymerization as a sticky agent for papermaking is closely related to the spinnability in an aqueous solution, as disclosed in JP-A-48-9005 and JP-A-52- 278
08, and the conventionally proposed method for improving the spinnability of an acrylamide polymer aqueous solution is a method of copolymerizing 2-acrylamide-2-medylpropane sulfonate. (Unexamined Japanese Patent Publication No. 5
2-37580), a method using an azo compound as a polymerization initiator in the presence of a heavy metal salt and/or a reducing inorganic phosphorus compound (JP-A-57-121007), and the like. It is shown in the illustrated examples that these proposed methods employ increasing the viscosity of the acrylamide polymer aqueous solution as a technical solution to improve the stringiness. .

Acrylamide polymers with a high degree of polymerization are also used as coagulating and dehydrating agents. Among them, for the acrylamide polymer containing ammonium acrylate, a method has been reported in which the acrylamide polymer containing ammonium acrylate is polymerized as an aqueous solution at pH 10.7 with 0.1% ammonium hydroxide for the purpose of obtaining a high molecular weight polymer (JP-A (Sho 48-31281).

Also, an aqueous solution copolymer of acrylic acid with an alkali salt or ammonium salt or a mixture thereof (JP-A-5
5-40749) and a method for producing a swelling material by polymerizing a solution of acrylic acid with alkali or ammonium or both and water without using a crosslinking agent has been reported (Japanese Patent Laid-Open No. 55-58208). ).

However, these polymers are polymerized with ammonium acrylate alone or in combination, but the improvement in spinnability is insufficient, and some polymers have extremely long spinnability. It cannot be said that they necessarily have excellent performance as agents.

[Problem to be solved by the invention] Generally, aqueous solutions of water-soluble polymers with a high degree of polymerization exhibit high viscosity, but polymers with a high degree of polymerization tend to form gels that are insoluble in water. When the combined aqueous solution is used industrially, it often causes clogging of equipment piping and pumps, and when used as a sticky agent for papermaking, it often causes various problems such as staining papermaking blankets.

In addition, the method using 2-acrylamido-2-methylpropanesulfonate requires the use of an expensive compound in an optimum copolymerization amount of 6 to 8% by weight, making it an inexpensive and industrially effective polymer. This method is not necessarily suitable as a method for producing a composite.

In order to obtain a water-soluble acrylamide polymer whose aqueous solution exhibits high stringinability, the present inventors have discovered that the polymer has excellent solubility in water without substantially increasing the degree of polymerization, that is, the viscosity of the aqueous solution, and is inexpensive. We have conducted extensive research on methods that can be used to manufacture this product.

(B) Structure of the Invention [Means for Solving the Problems] The present inventors have diligently studied the means for solving the above problems, and found that the above problem has been solved by two types of acrylic acid consisting of ammonium acrylate and other acrylates. The present invention was completed by discovering that the problem could be solved by copolymerizing the acid salt with acrylamide to form an acrylamide copolymer.

That is, the present invention relates to the viscosity of a 1% aqueous solution containing ammonium acrylate and an acrylate other than ammonium acrylate as a constituent monomer and measured with a B-type viscometer (rotation speed 12 rpm: rotor 3: temperature 25°C). is 500
The present invention relates to an acrylamide copolymer characterized in that it has a viscosity of cps or higher, as well as a sticky agent for papermaking and a coagulation dehydrating agent comprising the copolymer.

○Acrylate The acrylamide copolymer of the present invention is a copolymer of two types of acrylates consisting of ammonium acrylate and other acrylates with acrylamide, but acrylates other than ammonium acrylate Examples include alkali metal salts such as sodium and potassium salts, and alkaline earth metal salts such as magnesium, and alkali metal salts are preferred in the present invention. That is, an acrylamide/ammonium acrylate/alkali metal acrylate copolymer is preferred for the present invention.

Among the copolymers having the above structure, the monomer content is preferably 5 to 30 molχ, more preferably 10 to 30 molχ, particularly preferably 15 to 27 molχ.
A water-soluble acrylamide copolymer is obtained by polymerizing a monomer mainly composed of acrylamide containing an acrylate of olχ, and ammonium acrylate is preferably 2 to 60 moIχ based on the total amount of acrylate, more preferably 5 to 40 molχ, particularly preferably 10 to 35 molχ
It is contained.

The acrylamide copolymer of the present invention having the above structure has improved solubility and spinnability without increasing the viscosity of the acrylamide polymer.

In other words, an acrylamide copolymer produced using two types of acrylates (one of which is ammonium acrylate) has a higher level of performance than a conventionally known polymer obtained by polymerizing sodium acrylate and acrylamide. The viscosity of the aqueous solution is equivalent to that of a polymer to which ammonium acrylate is not added, but the aqueous solution has an extremely excellent spinnability.

When the acrylamide copolymer of the present invention is used as a sticky agent for papermaking, it forms a good paper layer with no wash-off phenomenon, does not tend to adhere to the dryer surface, does not cause paper breakage, and has excellent properties. It can be used as a sticky agent for paper making.

Furthermore, when the acrylamide copolymer of the present invention was used as a coagulation-dehydrating agent, it was found to be excellent in coagulation-sedimentation properties, particularly in a coagulation-sedimentation test of papermaking wastewater.

It has been reported that a copolymer of 2-acrylamide-2-methylpropanesulfonate and acrylamide is an excellent flocculant, and that the longer the stringiness is, the faster the flocculation sedimentation rate is. Kaisho 52-375
80).

The present invention provides a coagulating dehydrating agent having similar performance by using inexpensive ammonium acrylate.

In addition, copolymers obtained by polymerizing monomers in which the amount of acrylate in the monomer is less than 5 mol χ have a small degree of the above effect, and copolymers obtained by polymerizing monomers in which the amount of acrylate in the monomer exceeds 3 Q mol χ Copolymers improve spinnability, but are undesirable because they increase viscosity. Furthermore, if the amount of ammonium acrylate is less than 2 molχ based on the total 1 of the acrylate, the effect of improving stringiness is small, and if it exceeds 60 molχ, the stringiness and solubility will deteriorate, which is not preferable.

Further, as the acrylamide copolymer of the present invention, a copolymer having an absolute colloidal equivalent value in the range of 0.7 to 4.5 meq/g is preferable, more preferably 1.3 to 4.5 meq/g.
3.9 meq/g, particularly preferably 2.0 to 3
．． 5 meq/g.

In addition, the acrylamide copolymer of the present invention can be used as a coagulating dewatering agent, a sticky agent for papermaking, a soil conditioner, a thickener, an oil recovery agent, etc., especially for papermaking, by taking advantage of the property that it can form a highly viscous aqueous solution. B type viscometer (rotation speed 12
rpm: Rotor 3: 1% measured at temperature 25°C)
The polymer needs to have an aqueous solution viscosity of 500 cps or more, more preferably 3000 cps or more.

Although it is desirable to have a higher viscosity, an upper limit is naturally set from the viewpoint of manufacturing possibility or ease.

Other monomers For the acrylamide copolymer of the present invention, if necessary, for example, alkali metal salts or ammonium salts such as sodium salt of styrene sulfonic acid, sulfoethyl acrylate, etc., as long as the properties of the polymer are not deteriorated. Alkali metal salts such as sodium salts or ammonium salts of sulfoalkyl (meth)acrylates such as, vinyl acetate and N-alkylacrylamides such as N,N-dimethylacrylamide, acrylic esters such as methyl acrylate, methyl methacrylate, etc. It is also possible to use a copolymer obtained by further copolymerizing one or more monomers selected from water-soluble or water-insoluble monomers such as methacrylic acid ester, and methoxyethyl acrylate.

○Production method The acrylamide copolymer of the present invention can be produced by a known method.

0 For example, known polymerization methods such as aqueous solution polymerization, reverse-phase emulsion polymerization, and reverse-phase suspension polymerization can be used for polymerization. However, when considering the product price, the aqueous solution polymerization method is preferable, but if the product price is ignored, known polymerization methods such as reverse-phase emulsion polymerization and reverse-phase suspension polymerization can also be employed.

In the aqueous solution polymerization, the concentration of the monomer in the aqueous solution is preferably 1
5% by weight or more, more preferably 17 to 40% by weight, of known polymerization catalysts, such as azobisamidinopropane hydrochloride, ab-based catalysts such as abbicyanovaleric acid, peroxide-based catalysts such as persulfates, and even Polymerization is usually carried out at a polymerization initiation temperature of 0 to 25°C using a combination of an azo catalyst or a peroxide catalyst and a reducing agent such as sulfite. The amount of catalyst used is generally 100 to 6000 ppm for azo systems based on the monomer.
m, 1 to 200 ppm for peroxide systems, and about 1 to 200 ppm for reducing agents used in combination.

If necessary, alcohol amines, mercaptans,
Substances required in conventional methods, such as chain transfer agents such as amines, urea and their derivatives, sodium sulfate, salt, polyethylene glycol, and even surfactants, may be present in the polymerization system.

Generally, in the case of aqueous polymerization, the peak temperature reaches 75 to 95°C, so that the acrylamide component partially undergoes hydrolysis and is converted into anionic units.

Therefore, the colloidal equivalent value of the obtained polymer is approximately 0.2 to 0.0% higher than the colloidal equivalent value expected from the charging composition.
．． 8 meq/g higher. Therefore, at the time of preparation, the composition of the acrylate salt must be set lower than the monomer composition that provides the target colloidal equivalent value. Further, since the monomers are converted as described above, the composition ratio of the monomers constituting the copolymer in the present invention is based on the amount at the time of preparation.

According to aqueous solution polymerization, a rubber-like elastic body containing a large amount of water is obtained, which is ground into small pieces using a known method such as a chopper, and then processed by hand or with equipment such as a rotary dryer to 50% It is dried with hot air at ~120° C. to a solid content of 85% or more, and then pulverized into a powder of 15 meshes or less using a known pulverizer such as a roll pulverizer.

2. Before the drying step, a method can also be adopted in which the material is dehydrated with an alcohol such as methanol or ethanol, or acetone, and then dried.

○Usage method When the acrylamide copolymer of the present invention is used as a sticky agent for papermaking, it is usually prepared in advance in a dissolution tank at a concentration of 0.03 to 0.
It is dissolved at a concentration of 5%, preferably 0.05 to 0.2%, and diluted 2 to 10 times as necessary before use, and supplied to a stage prior to the papermaking process, such as a circular mesh hat. be done. The amount added is usually 0.01 to 2% by weight based on the paper stock.

The sticky agent for papermaking of the present invention can also be used in combination with known sticky agents such as polyethylene oxide and sagebrush. Also, known methods can be used to form sized paper. Furthermore, it is also possible to use known internally added and externally added dryer release agents in combination to improve the releasability from the dryer.

As the paper machine, known paper machines such as a cylinder paper machine, a short wire paper machine, a Fourdrinier paper machine, and a former paper machine can be used.

A Yankee dryer is generally used as a dryer in the production of household paper such as toilet paper, dust paper, tissue paper, etc., but a paper machine equipped with a multi-tube dryer can also be used.

Furthermore, when the acrylamide copolymer of the present invention is used as a coagulating and dehydrating agent, it can be used alone for wastewater treatment in various manufacturing processes such as paper manufacturing, mining, civil engineering, metals, etc., like general anionic flocculants.

It can also be used as a cation/anion combination system and tertiary treatment for sewage and human waste.

It has been found that the acrylamide copolymer of the present invention exhibits excellent performance in the coagulation and sedimentation of papermaking wastewater, particularly due to its long stringability.

U action] By copolymerizing two types of acrylates consisting of ammonium acrylate and other acrylates with acrylamide, the acrylamide polymer has excellent stringability and solubility that other polymers do not have. , and can be applied without changing the viscosity of the aqueous solution.

[Example] Examples will be described below along with comparative examples.

Comparative Example 1 1 kg of an aqueous solution of acrylamide and sodium acrylate having a composition of 83 mol x: 17 mol x and a monomer concentration of 25% was placed in a stainless steel dewar bottle. After adjusting the temperature of the aqueous solution to 15° C., nitrogen was introduced and degassed for 90 minutes. As a catalyst, azobisamidinopropane hydrochloride was added at 4000 ppm based on the total amount of monomers. Polymerization was completed 110 minutes after the temperature started to rise, so the resulting gel was taken out and ground into a mountain shape using a small chopper.
It was dried for 3 hours in a hot air dryer at 80°C. The obtained solid was pulverized and the viscosity, colloid equivalent value, stringiness, and amount of undissolved matter of the aqueous solution were measured, and the viscosity was 5650c.
ps, colloid equivalent value -3.05 meq/g, stringiness 1
25 mm, and the amount of undissolved matter was less than one.

The viscosity, stringiness, and amount of undissolved matter were measured as follows.

After diluting 4 g of powder with 400 rd distilled water and stirring for 3 hours, the temperature was adjusted to 25° C. and measured using a B-type viscometer at a rotation speed of 12 r and a rotor of 3.

After diluting 2 g of stringable powder with 400 ml of distilled water and stirring for 3 hours, the temperature was adjusted to 25°C, and the container was set on a platform that lowered the mixture at a rate of 5 mm/sec, and then fixed on a support platform. A glass ball with a diameter of 10 mm is immersed to a depth of about 20 mm, and the solution is lowered at a speed of 5 mm/sec to stretch the solution into a thread, and from the time the bottom end of the glass ball reaches the surface of the solution. Time until the thread breaks T (sec
) was measured, and the stringiness was calculated using the following formula.

Threadability (mm) - 0.5g of 5XT Fuyuryushoyo powder was diluted with 500ml of distilled water, stirred for 3 hours, and the entire solution was filtered through a 83-mesh sieve with a diameter of 20cm, washed with water, and passed through the sieve. The remaining undissolved matter was collected and placed in a cylinder, and the volume was measured.

5 6 Examples 1 to 12, Comparative Example 2 Polymerization was carried out in the same manner as in Comparative Example 1 except that the charging composition was changed. The results obtained are summarized in Table 1, including the results of Comparative Example 1.

(The following is a blank space) 7 Comparative Example 3, Examples 13 to 14 Polymerization was carried out in the same manner as in Comparative Example 1 except that the charging composition, catalyst, and adjustment temperature were changed. As catalysts, 2000 ppm of sodium azobiscyanovalerate and 35 ppm of ammonium persulfate were used. The adjustment temperature is 10°C. The obtained results are summarized in Table-2.

Comparative Example 4 Polymerization was carried out in the same manner as in Comparative Example 1 except that the monomer concentration, charging composition, and catalyst were changed. Monomer concentration is 27.5
It was adjusted to % by weight. The catalyst was 2000 ppm of sodium azobiscyanovalerate and 300 ppm of ammonium persulfate.
ppm was used. The obtained results are summarized in Table-2.

(Leaving space below) 9 Comparative Use Example 1, Use Examples 1 to 5 Using the polymers obtained in the above Comparative Examples and Examples, the amount of free water was determined using a Canadian standard freeness meter to determine its performance as a sticky agent for papermaking. The degree of effectiveness was confirmed by calculating the degree of freeness as described in JP-A No. 54-163524. In the experiment, a 0.3% by weight pulp slurry of beaten NBKP was added to a Canadian standard freeness (JIS-P8121) 545d.
．． Add 1% by weight of the above polymer aqueous solution to 0.05%, 0.15%, and 0.3% by polymer weight based on the amount of pulp in the slurry.
0% was added, and the amount of free water (V) at this time was measured using a Canadian standard freeness meter. The freeness was calculated using the following formula.

The larger the value of surface/reverse water content, the greater the effect as a sticky agent for papermaking. The results obtained are summarized in Table 3.

(The following are blank spaces) Use Comparative Examples 2 to 4, Use Examples 6 to 8 Using the polymers obtained in the above Comparative Examples and Examples, the following adjusted wastewater was tested for performance as a coagulating dehydrating agent.

The adjusted wastewater is pulp wastewater (COD380ppm: pH3
,70)500mj! A predetermined amount of Hunt sulfuric acid was added to the solution, stirred, and adjusted to pH 6 with saturated lime water. A predetermined amount of a 0.1% aqueous solution of the polymers of Comparative Examples and Examples shown in Tables 1 and 2 is added to the treated wastewater. Stir with a jar tester at 120 rpm for 1 minute to generate flocs. The mixture was further stirred at 50 rpm and the diameter of the generated flocs was observed. After stirring, the time required for the flocs to sink 5 cm from the water surface is measured to determine the settling rate. After standing still for 30 minutes, the COD of the supernatant water is measured. The results obtained are summarized in Table 4.

It can be seen that the copolymer of ammonium acrylate, sodium acrylate, and acrylamide has an excellent effect on reducing sedimentation time, filtrate clarity, and COD in coagulation and sedimentation of conditioned wastewater.

(The following is a blank space) 3 (c) Effects of the invention According to the present invention, an acrylamide polymer with high spinnability can be produced at low cost, and can be used not only as a sticky agent for papermaking and a flocculating dehydrator, but also as a soil conditioner. It is expected to have a wide range of uses as a drug in the field.

Claims (1)

[Claims] 1. Contains ammonium acrylate and acrylates other than ammonium acrylate as other constituent monomers, and was measured with a B-type viscometer (rotation speed 12 rpm: rotor 3: temperature 25 ° C.) The viscosity of a 1% aqueous solution is 500 cps
An acrylamide copolymer characterized by the above. 2. A sticky agent for papermaking comprising the acrylamide copolymer according to claim 1. 3. A coagulating dehydrating agent comprising the acrylamide copolymer according to claim 1.