JPS62280B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a novel acrylamide-based paper strength agent in which acrylamide monomer or both acrylamide and acrylonitrile monomers are substantially removed. Acrylamide or a monomer mixture of acrylamide and a vinyl compound copolymerizable with it is easily polymerized to produce a water-soluble high molecular weight polymer. These polymers have traditionally been used in the paper manufacturing industry as additives to improve the workability of the papermaking process and to improve various strengths and paper qualities of paper.In particular, acrylamide-based polymers have been used as anionic dry paper strength-enhancing additives. agents are widely known. Acrylamide-based polymers used as dry paper strength agents are generally copolymers of acrylamide and acrylates or partial hydrolysates of polyacrylamide, but recently there have been improvements in quality and reductions in price. For this purpose, copolymers containing acrylamide as a main component and acrylonitrile or more have come to be widely used. Polymerization is usually carried out by an aqueous solution polymerization method at a monomer concentration of 5 to 30% by weight and a polymerization temperature of room temperature to 80°C.
The polymerization is carried out using a common water-soluble radical generating catalyst as a polymerization initiator, such as peroxides such as potassium persulfate, ammonium persulfate, hydrogen peroxide, and tertiary hydroperoxide. Depending on the polymerization conditions, amines such as dimethylaminopropionitrile and triethanolamine, or reducing agents such as ferrous sulfate, sodium bisulfite, L-ascorbic acid, β-diketones and their tautomers were used in combination. , so-called redox initiators may also be used. Polymerization is completed in one to several hours, and the polymerization product is obtained as a viscous aqueous solution. Acrylamide-based paper strength enhancers are usually commercialized in the form of this viscous aqueous solution; for example, dry paper strength enhancers are said to have a molecular weight of about 500,000 to 1,000,000. However, in a polymerization reaction, it is generally extremely difficult to achieve a 100% reaction rate, and usually a small amount of monomer remains. Especially 1
Compared to homopolymerization of different types of monomers, when copolymerizing two or more types of monomers, a considerable amount of monomer remains even if left for a long time after the completion of the polymerization reaction, such as acrylamide. , in the ternary copolymerization of acrylate and acrylonitrile, each monomer is 0.5
It is not uncommon for some weight percent to several weight percent to remain.
In addition, since paper strength enhancers are mostly liquid products that remain polymerized as described above, they tend to contain more residual monomers than powder products such as polymer flocculants. Acrylamide monomer has recently attracted attention as a poisonous substance that causes dermatitis and nerve damage, and acrylamide monomer contained in acrylamide-based polymer products has become a problem in terms of pollution prevention. For example, when it comes to paper strength agents, the acrylamide monomer in the product
There is a voluntary regulation among manufacturers that the content should be 0.2% (per resin content) or less. For this reason, various methods have been proposed for reducing or removing unreacted acrylamide monomers from acrylamide-based polymers. For example, the most reliable and simplest method is known to be washing and extraction using a solvent that does not dissolve the polymer but only dissolves the acrylamide monomer, such as methanol. However, this method is not only applicable only to powdered products, but also has the drawback of increasing the product price due to the complexity of solvent recovery and other operations. There is also a method of converting unreacted acrylamide monomers into other harmless substances by adding substances that selectively react with acrylamide monomers, such as ammonia, amines, bisulfites, etc.
No. 2646, U.S. Patent No. 2960486, and JP-A No. 50-40689), in addition to redox polymerization initiators conventionally used as catalyst systems, a combination method with azo polymerization initiators. , a method in which a high-temperature decomposition type initiator is used in combination to prevent reaction termination at the final stage of polymerization (Japanese Patent Publication No. 47-26430, Japanese Unexamined Patent Application Publication No. 1983-1989)
-44280 and the specification of JP-A-50-96689). Although these methods are quite effective in reducing acrylamide monomers, it is difficult to improve the polymerization rate in multicomponent copolymerization, such as paper strength agents, compared to homopolymerization.
The reduction in acrylamide monomer is still not sufficient. Furthermore, with regard to recent paper strength agents, copolymers with acrylonitrile added as mentioned above are commercially available as general-purpose types, and in this copolymer, the residual amount of acrylonitrile monomer is higher than that of acrylamide monomer. There are more and more. These known methods are also unsatisfactory in this respect, since acrylonitrile monomers are more toxic than acrylamide monomers. The toxicity of these monomers is
Acrylamide has an LD _{50 of} 170 mg/Kg (rat, oral) and acrylonitrile has an LD ₅₀ of 93 mg/Kg (rat, oral) (Merck Index 9th edition).
(See page 17). The present inventors have conducted various studies to eliminate the drawbacks of these conventional methods and to develop a method that can decompose and remove not only acrylamide monomer but also acrylonitrile monomer. It has been found that unreacted acrylamide monomers and acrylonitrile monomers in the acrylamide-based paper strength agent can be substantially completely removed by doing so. The present invention is based on this knowledge, and provides a partial hydrolyzate of polyacrylamide and/or a copolymer containing acrylamide as a main component and optionally acrylonitrile, and a polymer reaction modified product thereof, and acrylamide monomer decomposition ability. unreacted acrylamide monomer and optionally unreacted acrylonitrile monomer in the polymer, characterized in that the active ingredients are actinomycetes having the ability to decompose acrylonitrile monomer or an enzyme thereof, and optionally a bacterium having the ability to decompose acrylonitrile monomer or an enzyme thereof. This is an acrylamide-based paper strength agent that can substantially remove polymers. If the acrylamide copolymer contains acrylonitrile, both monomers can be removed by combining actinomycetes or their enzymes capable of decomposing acrylamide monomers with bacteria or their enzymes capable of degrading acrylonitrile monomers. can be effectively removed. The acrylamide polymer used in the present invention is a partially hydrolyzed product of polyacrylamide, a copolymer containing acrylamide as a main component, a modified product thereof by polymer reaction, or a mixture thereof. As the comonomer, any compound can be used as long as it is copolymerizable with acrylamide. For example, the following comonomers can be used. methacrylamide, (meth)acrylic acid, salts of (meth)acrylic acid, esters of (meth)acrylic acid,
N-derivatives of (meth)acrylamide, (meth)acrylonitrile, (meth)acrolein, allylamine, vinyl acetate, vinyl chloride, vinylidene chloride, vinylpyridine, vinyl alkyl ether,
Styrene and its derivatives, vinyl sulfonic acid and its derivatives, salts of these sulfonic acids, etc. In addition to the above-mentioned compounds, for example, the following compounds can be used as comonomers. As the ester of (meth)acrylic acid, monohydric or polyhydric alcohols such as methyl, ethyl, propyl,
Esters of butyl, hydroxyethyl or hydroxypropyl alcohol, esters of amino alcohols such as dimethylamino or diethylaminoethanol, dimethylamino or diethylaminopropanol or triethanolamine, N-derivatives of (meth)acrylamide such as (meth)acrylic Amides of acids and alkylene diamines, such as N-dimethylaminoethyl- or N-diethylaminopropyl-(meth)acrylamide, and also N-methylol-(meth)
Acrylamide or 2-(meth)acrylamido-2-methylpropanesulfonic acid, vinyl alkyl ethers such as vinyl methyl ether or vinyl ethyl ether, styrene derivatives such as α-methylstyrene or vinyltoluene, vinylsulfonic acid derivatives such as Vinylbenzenesulfonic acid or vinyltoluene-α-
Sulfonic acid. Salts of (meth)acrylic acid and the above-mentioned sulfonic acid compounds include preferably alkali metal salts, water-soluble (or in an amount that does not make them insoluble) alkaline earth metal salts or ammonium salts, especially sodium salts. Comonomers having amino groups, such as aminoalkyl esters of (meth)acrylic acid or N-dialkylaminoalkyl-(meth)acrylamides, can be prepared by reacting with acids, ammonium chloride, dimethyl sulfate, diethyl sulfate, methyl chloride, etc. A quaternary ammonium compound may also be used, or it may be copolymerized and then quaternized. The above comonomers are appropriately selected depending on the properties of the resulting copolymer, such as water solubility, anionicity, or cationicity, and can be copolymerized with acrylamide alone or in combination of two or more.
Homopolymerization and copolymerization of acrylamide can be performed using any known method and conditions.
Partially hydrolyzed products of polyacrylamide prepared by conventional methods, partially hydrolyzed products of acrylamide copolymers, etc. can also be used as polymer reaction-modified products. The bacteria that have the ability to decompose acrylamide monomer used in the present invention have particularly high activity among the bacteria that have the ability to decompose and assimilate acrylamide monomer, which the present inventors previously isolated from soil, well water, etc. Katata No. 10021 bacterium, its related bacteria, and mutant strains. Bacterium No. 10021 has been deposited as Microtechnology Research Institute Bacteria No. 3451, and its taxonomic, physiological, and biochemical properties are described in detail in Japanese Patent Application No. 150738/1983. Bacteria No. 10021 having the properties described in the above specification, including its related bacteria and mutant strains, will also be referred to as "actinomycetes capable of decomposing acrylamide monomer" in the present invention. In other words, as long as it has the ability to resolve acrylamide.
In addition to Bacterium No. 10021, related bacteria and mutant strains thereof can be used in the present invention. As with these bacteria, their enzymes are also used. Extraction, separation, purification, etc. of the enzyme can be carried out by the method described in Japanese Patent Application No. 51-20029. In the present invention, crude oxygen may be used. When an acrylamide copolymer containing acrylonitrile as a comonomer is a paper strength agent component, both the acrylamide monomer and the acrylonitrile monomer remain as described above.
The paper strength enhancer of the present invention contains, in addition to the above-mentioned actinomycetes having the ability to decompose acrylamide monomer, also bacteria having the ability to decompose acrylonitrile monomer. Bacteria that have the ability to degrade acrylonitrile monomers are often found among bacteria that have nitrile-degrading activity. For example, bacteria having nitrile decomposition activity are as described in Japanese Patent Publication Nos. 37-4495 and 49-28377, and the specifications of JP-A-49-33472 and 50-53586. Bacterial genera such as Pseudomonas, Xanthomonas, Micrococcus, Corynebacterium, Alcaligenes, Achromobacter, Aerobacter, Nocardia, Brevibacterium, Bacillus, and Bacteridium are known. . Any of these bacteria that has the ability to decompose acrylonitrile monomer can be used in the present invention, and in this case as well, the enzyme or crude enzyme may be used. Some of the bacteria that have the ability to decompose acrylonitrile monomer have some ability to decompose acrylamide monomer by themselves, but their activity is so small that they are not practical for decomposing acrylamide monomer. In other words, this type of bacteria normally decomposes nitriles into amides fairly quickly, but the subsequent decomposition is extremely slow. Therefore, when actinomycetes that have the ability to decompose acrylamide monomer and bacteria that have the ability to decompose acrylonitrile monomer coexist, the latter decomposes acrylonitrile into acrylamide.
Since the former decomposes acrylamide, both monomers can be decomposed and removed very effectively. Acrylamide-based paper strength agents produced by known methods are usually pasty liquid products;
As mentioned above, the resin contains 0.5% to several% by weight of unreacted acrylamide and other monomers. The amount of the actinomycetes having the ability to decompose acrylamide monomer, the bacteria having the ability to decompose acrylonitrile monomer, or their enzymes to be used as defined above is:
Although it varies slightly depending on the amount of acrylamide monomer and acrylonitrile monomer remaining in the polymer, it is usually 0.001 to 5% by weight for Bacterium No. 10021, preferably 0.01 to 5% by weight based on the resin solid content. It is added in an amount of 1% by weight. If the unreacted monomer contains acrylonitrile, 0.05 to 10% by weight of acrylonitrile-degrading bacteria such as Brevibacterium imperiale IAM1654, preferably
It is added in an amount of 0.05-1% by weight. When using crude enzymes, etc., the degrading activity of each monomer is concentrated compared to when using bacterial cells, so the amount used is generally 1/2 to 1/4 of the amount of bacterial cells. That's enough. In addition to the above-mentioned components, the paper strength agent of the present invention may contain conventional additives such as polymer thermal deterioration inhibitors, solubilizing agents, etc. in conventional amounts. To produce the paper strength agent of the present invention, for example, the above-mentioned acrylamide-based polymer and the above-mentioned bacteria or their enzymes are mixed as a dry product with some of the substrate remaining, if desired, by a common powder mixing method. Alternatively, bacteria or their enzymes may be directly added to and mixed with a solution or paste of the polymer in an aqueous medium. The novel paper strength agent mixture thus produced is preferably stored at room temperature or cold, and an enzyme stabilizer may be added. In the present enhancer in a dry state, the monomer decomposition ability of the bacterial cell enzymes described above is generally not exhibited, but in the state of a solution or paste in an aqueous medium, unreacted monomers are dissolved in the medium. Therefore, the acrylamide monomer or the acrylonitrile monomer is substantially completely decomposed and removed by the enzymatic action of the bacteria in a relatively short period of time, usually within several hours. The paper strength agent of the present invention can be used in paper making by dissolving or diluting it in an aqueous medium in the same manner as ordinary acrylamide-based paper strength agents. It does not adversely affect the performance of the force enhancer. Most of the acrylamide-based paper strength agents are liquid products (visible viscosity
100 to 10,000 cp) and are stored, so if bacteria or enzymes are added and mixed to a liquid product manufactured by a conventionally known method or a liquid commercial product and left at room temperature, it usually lasts for several days during storage. It is possible to substantially decompose and remove unreacted monomers within a certain period of time.
Furthermore, when the acrylamide polymer paste is diluted with an aqueous medium and used for paper making, bacterial cells or enzymes may be added immediately before dilution (usually about 10 times). This case is particularly advantageous because unreacted monomers can be effectively decomposed and removed at room temperature in a very short time, usually within a few hours, due to the reduction in viscosity due to dilution and the improvement in contact efficiency due to mixing. . Therefore, from the viewpoint of ease of handling during use, effect of decomposing unreacted monomers, and other aspects, in a preferred embodiment of the paper strength enhancer of the present invention, an acrylamide polymer or a paste thereof and each of the above-mentioned bacteria or its The enzymes are stored separately and the two are brought together at the time of use. In this case, they can be combined in various ways, but
Although the solid polymer and the bacteria or enzyme are mixed and then dissolved, it is preferred to add the bacteria or enzyme to the polymer paste, especially just before diluting it. These methods are particularly applied when the product is in liquid or paste form and is likely to deteriorate due to high temperature storage, and thus deterioration due to high temperature storage can be avoided. In addition, when using dried bacterial cells, the purpose can be achieved in a short time by stirring while aerating during dissolution, dilution, and treatment. Parts and percentages in the examples below relate to weight. Quantification of acrylamide monomer and acrylonitrile monomer was performed by gas chromatography. That is, the paper strength enhancer is diluted with water to a predetermined concentration (usually 5 to 10 times, although it varies depending on the amount of residual monomer), and dilute sulfuric acid is added to this.
Adjust the pH to 1 to 2, close the mixer in a mixer, stir and mix for 2 to 3 minutes, then let stand, and use the supernatant liquid as the sample solution. The measurement was carried out using a Perkin Elmer F11 model under the following conditions.

[Table] In order to investigate whether the addition and mixing of bacterial cells or enzymes affected the effectiveness of the paper strength enhancer, LBKP (broad-leaved bleached kraft pulp) was used and JIS P-
The various strengths of paper made according to 8209, the tearing length is
Measurement was made according to JIS P-8113, specific rupture degree according to JIS P-8112, folding strength according to JIS P-8115, tear strength according to JIS P-8116, and sizing according to JIS B-8122. In addition, the viscosity was measured using a B-type viscometer in order to simply examine the difference in performance. Example 1 90 parts of acrylamide and 10 parts of acrylic acid were dissolved in water, the pH was adjusted to 7.0 with caustic soda solution, and the total amount was
The total was 945 copies. To this were added 5 parts of dimethylaminopropionitrile and 50 parts of 10% ammonium persulfate, and polymerization was carried out at 30°C for 2 hours. The viscosity of the resulting aqueous copolymer solution was 1000 cp at 25°C, and the amount of unreacted acrylamide monomer was 0.8% based on the resin content.
Bacteria No. 10021 was added to this aqueous solution as dried bacterial cells.
Add 0.03 part and stir to mix until homogeneous.
It was left at room temperature with occasional stirring. When the amount of acrylamide monomer was measured after 24 hours, it was hardly detected and was essentially 0 ppm. The viscosity of the polymer at this time remained unchanged at 1000 cp (25°C), and the strength-enhancing effect on the paper was also the same as that without the addition of microbial cells. Example 2 0.01 part of crude enzyme from Bacterium No. 10021 was added to 1000 parts of the copolymer aqueous solution of Example 1, treated in the same manner as in Example 1, and the amount of acrylamide monomer was measured 24 hours later. , almost undetectable. Moreover, the apparent viscosity and paper strength enhancement performance of the copolymer at this time were almost the same as those without the addition of crude enzyme. Example 3 A 10% copolymer aqueous solution having an apparent viscosity of 2700 cp and having a weight ratio of acrylamide: acrylonitrile: sodium methacrylate = 70:20:10 was prepared. This product contains unreacted acrylamide monomer and acrylonitrile monomer per resin.
Contained 0.5% and 2.5%. Add 0.02 parts of bacteria No. 10021 and 0.4 parts of Nocardia rubropercincta IFM33 cells (both as dry cells) to this aqueous copolymer solution, stir and mix to make a homogeneous state, and store at room temperature. did. Two days later, the amount of each monomer remaining in this aqueous solution was measured, and the amount of acrylamide monomer was substantially 0 ppm, and the amount of acrylonitrile monomer was 0.001%. The viscosity and paper strength enhancement performance of the copolymer aqueous solution at this time are as follows:
There was no difference at all from those to which no bacterial cells were added. Example 4 Commercially available anionic paper strength agent (15% resin content, visible viscosity 850 cp, 0.4% acrylamide monomer and 1.8% acrylonitrile monomer per resin content) 1000
0.1 part of bacteria No. 10021 and 0.5 part of Brevibacterium imperiale IAF1654 cells (both as dry cells) were added to the solution, and diluted 10 times with water at room temperature while stirring and mixing. . At this time, it quickly dissolved to become a homogeneous aqueous solution. Approximately 60 minutes after the start of dilution, the amounts of acrylamide monomer and acrylonitrile monomer were measured while stirring the diluted solution gently, and both monomers were found to be below the limit of quantification and substantially 0 ppm. This diluted solution was directly added to a paper making solution to make paper. For comparison, paper was made in the same manner using a 10-fold diluted solution of the paper strength enhancer described above without the addition of each bacterial cell. Paper making was carried out as follows. LBKP as pulp
After beating to a degree of freeness of 400 c.c. as measured by the Canadian Freeness (CFS) method, 1% Size Pine E (rosin-based sizing agent manufactured by Arakawa Forestry Co., Ltd.), paper of the present invention or comparative paper was used. Force enhancer 0.5%
(as a resin component) and 2% sulfuric acid (PH4.5) were added, and then paper was made using a round Tatsupee standard sheet machine so that the basis weight was 60 g/m ² . Note that each amount added is the amount relative to the pulp. The results of measuring the paper strength of each paper thus obtained are shown in the following table. The various paper strengths of paper without paper strength enhancer additives are tearing length 5.3 km, specific rupture degree.
3.2, folding strength 45 times, tear strength 52g and size degree
It was hot in 30 seconds. The measured values in the table are indexes with the value in the case of no additives as 100, and it is recognized that even when the specific rupture degree and folding strength are increased, the tear strength hardly decreases.

【table】

Claims (1)

[Claims] 1. Partial hydrolyzate of polyacrylamide and/or
or a copolymer containing acrylamide as a main component and optionally containing acrylonitrile and/or a polymer reaction modified product thereof, an actinomycete or its enzyme capable of decomposing acrylamide monomer, and optionally a bacterium having an ability to decompose acrylonitrile monomer, or An acrylamide-based paper strength agent capable of substantially removing unreacted acrylamide monomers and optionally unreacted acrylonitrile monomers in the polymer, characterized in that the enzyme is used as an active ingredient. 2 Partial hydrolyzate of polyacrylamide and/
or a copolymer containing acrylamide as a main component and/or a polymer reaction modified product thereof, and an actinomycete or an enzyme thereof capable of decomposing acrylamide monomer as active ingredients, Claim 1 The paper strength enhancer described in Section. 3 Copolymers containing acrylamide as a main component and acrylonitrile and/or polymer reaction modified products thereof, actinomycetes or their enzymes that have the ability to decompose acrylamide monomers, and bacteria that have the ability to decompose acrylonitrile monomers or their enzymes. The paper strength enhancer according to claim 1, characterized in that it is an active ingredient.