JPH0541754B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a paper manufacturing method using a novel filler retention improver.In the paper manufacturing method of papermaking and drying a neutral or weakly alkaline aqueous pulp slurry containing filler, a special substance is used as a filler retention improver. , that is, a cationic polymer substance and 25~
By using two types of substances together, a highly anionic acrylamide polymer with a specific molecular weight and having 60 mol% of anionic groups, the filler yield can be improved extremely efficiently due to the mutual effect of these two types of substances. The present invention provides a papermaking method that achieves the above-mentioned effects. In general papermaking processes, various fillers are commonly used for the purpose of improving the whiteness and opacity of the paper, as well as imparting smoothness and flexibility. Even if only the filler added to the pulp slurry is added to make paper, most of the filler will flow out into the white water, resulting in an extremely low yield and the filler will not have the intended effect. , it also brings about great economic disadvantages. Therefore, in general papermaking processes where fillers are added, some kind of filler retention aid is usually used. By the way, in the so-called acidic papermaking method that uses acidic pulp slurry to which sulfuric acid is added, which is widely used to obtain general printing paper, the filler retention improver is mainly cationic water-soluble. Polymers such as polyethyleneimine, cationic polyacrylamide, polyamide polyamine epichlorohydrin resin, etc. have been effectively utilized. However, in recent years, paper obtained by the above-mentioned acidic papermaking method has poor weather resistance, and when made into printed materials, has poor storage stability and poor durability.
Limestone, the raw material for calcium carbonate, which is a filler used in the so-called "neutral papermaking method" in which paper is made with neutral or slightly alkaline conditions, is abundantly produced in Japan, and calcium carbonate is inexpensive and the filler has excellent effects. Due to these factors, even in the field of general printing paper, instead of the conventional acid paper making method that uses sulfuric acid, calcium carbonate is used as a filler, and sulfuric acid is not added at all, or even if it is added. There is increasing research into a "neutral papermaking method" in which only a small amount of carbon dioxide is added.
However, the above-mentioned various filler retention improvers that have been used in the conventional acidic papermaking method are
The current state of the industry is that the effect is not sufficient in the "neutral paper making method", and there is a new demand for the development of a filler retention improver that is sufficiently effective in the "neutral paper making method". From this point of view, as a retention improver for calcium carbonate, which is a filler in the "neutral paper making method",
JP-A-57-77399 proposes a high molecular weight copolymer of a (meth)acrylic acid ester having a quaternary ammonium group and acrylamide. The filler retention improver exhibits a relatively good retention effect in the high addition range of 0.1% or more based on the pulp weight, and the filler retention improver itself has a high molecular weight. It causes staining of wires and blankets in the papermaking process, the resulting paper has poor texture, and high additives increase chemical costs.Furthermore, in the low additive range of less than 0.1%, However, it has drawbacks such as an unsatisfactory yield improvement effect itself, and as a result, calcium carbonate filler, etc. It has a high retention-improving effect as a retention-improving agent, and has good operability when used.
Moreover, the reality is that a filler retention improver that has characteristics such as being economically usable has not yet been obtained. The present invention uses a cationic polymer substance and a highly anionic acrylamide-based polymer having a specific amount of anionic groups as a filler retention improver in the above-mentioned "neutral papermaking method," that is, contains a filler. In a paper manufacturing method for papermaking and drying a neutral or weakly alkaline aqueous pulp slurry, a highly anionic acrylamide-based material having a molecular weight of 100,000 to 1,000,000 and having a cationic polymer substance and 25 to 60 mol% of anionic groups is used. By using an aqueous pulp slurry containing a polymer, it has a high retention-improving effect as a retention-improving agent for calcium carbonate fillers, etc., and the resulting paper has good texture, and is easy to operate when using it. The present invention has been able to provide a paper manufacturing method using a filler retention improver that has good properties and can be used economically in terms of price. In the method of the present invention, any of the various known fillers used in conventional papermaking processes can be used, including clay, talc, titanium dioxide, calcium carbonate, aluminum hydroxide, and synthetic resin components. Plastic pigments, other organic or inorganic pigments, etc. can be used. In addition, the cationic polymer substances that can be used in the method of the present invention include various water-soluble or water-dispersible cationic polymer substances known as paper-making additives, specifically cation-modified starch, cationic Acrylamide-based polymers, cationic polyvinyl alcohol, polyethyleneimine or derivatives thereof, polyamines or reaction products of polyamide polyamines and epihalohydrin, etc., are used alone or in combination as appropriate. In particular, various cationic acrylamide-based polymers can be used depending on the cationic modification method, degree of cationic modification, molecular weight, type of comonomer, etc.; It exhibits the most excellent effect as a filler retention improver. This cationic acrylamide-based polymer can be produced by modifying an acrylamide-based polymer, that is, a water-soluble polymer containing acrylamide and/or methacrylamide as a main component, for example, by subjecting it to a Hoffman decomposition reaction or a Mannitz reaction, or Acrylamide and/or methacrylamide can be combined with various cationic comonomers, such as amino group-containing monomers such as alkylaminoalkyl (meth)acrylate, alkylaminoalkyl (meth)acrylamide, vinylpyridine, vinylimidazole, or their quaternized products. It can be easily obtained by copolymerizing with. The cationic acrylamide polymer, which is a filler retention aid used in the method of the present invention, does not need to have a particularly high molecular weight unlike filler retention aids commonly used in conventional acidic papermaking methods, and usually has a molecular weight of 1. The amount used is about 10,000 to 1,000,000, preferably about 100,000 to 600,000. This is because if the molecular weight of the cationic acrylamide polymer used as a filler retention improver is less than 10,000, the filler retention effect obtained in the method of the present invention may be insufficient; In the case of more than 10,000,
This is because even though the filler yield effect is good, there are negative effects such as contamination of wires and blankets during the papermaking process and deterioration of the texture of the paper obtained. One of the characteristics of the method of the present invention is that a sufficient filler retention effect can be obtained even when a cationic polymer substance whose molecular weight is not so high is used. The highly anionic acrylamide-based polymer, which is another type of filler retention aid used in combination with the cationic polymeric substance in the method of the present invention, is
Molecular weight 100,000~ with 60 mol% anionic group
1 million highly anionic acrylamide-based polymers that can be easily obtained by partial hydrolysis of acrylamide-based polymers or by copolymerization of (meth)acrylamide and comonomers containing anionic groups. Examples of the anionic group in the highly anionic acrylamide-based polymer include a carboxyl group, a sulfonic acid group, a phosphoric acid group, or a salt group thereof. Specific examples of the anionic group-containing comonomer include acrylic acid, methacrylate, etc. acid, crotonic acid, maleic acid, fumaric acid, itaconic acid, allylsulfonic acid, sulfomethyl(meth)acrylamide, styrenesulfonic acid, and salts thereof. The anionic group content of the highly anionic acrylamide polymer used as the filler retention aid used in the method of the present invention must be 25 to 60 mol%; This is because if the anionic group content of the anionic group is less than 25 mol %, the filler retention effect of the anionic acrylamide polymer will decrease rapidly. Furthermore, even if the anionic group content in the anionic acrylamide-based polymer exceeds 60 mol%, the filler retention effect exerted by the polymer tends to decrease, so that it cannot be used in the method of the present invention. The anionic group content of the anionic acrylamide polymer to be used is 25 to 60 mol%. In addition, if the molecular weight of the highly anionic acrylamide-based polymer is less than 100,000, the filler retention effect exerted by the polymer will be insufficient, and if it exceeds 1 million, it will be used for wire and blanket production in the papermaking process. Highly anionic acrylamide-based polymers with a molecular weight of 100,000 to 1,000,000 are used because there is a risk of such problems as inducing contamination and deterioration of the texture of the resulting paper. In the method of the present invention, the amounts of the above-mentioned cationic polymer substances and highly anionic acrylamide-based polymers may be changed as appropriate depending on the papermaking conditions, but in general, the amounts of the bone-dry pulp in the aqueous pulp slurry About 0.01 to 3% by weight is effective. Of course, the optimum amount and ratio of both may vary depending on the type of cationic polymer material or highly anionic acrylamide polymer used, and the conditions of the pulp slurry used, so the present invention Prior to carrying out the method, it is preferable to conduct a preliminary test and determine in advance the amount of each filler retention aid to be used. In addition, although the ratio of the cationic polymeric substance used as a filler retention improver to the highly anionic acrylamide-based polymer is not particularly specified, About 0.2 to 2 parts by weight of the acrylamide polymer is most commonly used. In the method of the present invention, the above-mentioned cationic polymer substance as a filler retention improver and highly anionic acrylamide-based polymer are sequentially added to an aqueous pulp slurry, which is a neutral to weakly alkaline raw material for papermaking. This paper-making method involves adding an effective amount of filler or adding it simultaneously, thoroughly mixing and dispersing the resulting pulp slurry, and then drying the resulting pulp slurry. This method achieves an extremely efficient increase in filler retention. The filler can be mixed at any stage of preparing the neutral papermaking raw material pulp slurry. Of course, in addition to the above-mentioned various additives, other additives may be added in combination as appropriate, but the effect of improving the filler retention by the method of the present invention will be limited to aqueous pulp slurry with a pH of less than 6. However, when a large amount of sulfate is added, the effect is significantly diminished, so when applying the method of the present invention, strict caution is required when using sulfate. Furthermore, when applying the method of the present invention, even in an aqueous pulp slurry with a pH of 6 or higher, the addition of a large amount of sulfuric acid causes the polymer chains of the highly anionic acrylamide polymer added as a filler retention aid to shrink. Since it will reduce the filler retention effect exerted by the polymer, it is necessary to avoid increasing the amount of sulfate as much as possible, and at most 0.5% by weight of absolute dry pulp.
It is desirable to keep it below. In the paper manufacturing method of the present invention, as described above, a cationic polymer substance is used as a filler retention improver,
It is used in combination with a highly anionic acrylamide-based polymer having 25 to 60 mol% of anionic groups, and even if one of these two types of filler retention improvers is missing, the present invention The effect of improving filler yield, which is the purpose of the method, is no longer sufficient. In addition, for example, in the manufacturing method of paperboard using sulfuric acid, that is, in the acidic paper making method, cationic polymeric substances and anionic polymeric substances are used as paper strength enhancers in order to improve the strength of the paper. A method of papermaking and drying an aqueous pulp slurry containing a combination of In the method of the present invention, even if a known low anionic acrylamide polymer is used as the paper strength enhancer in place of the highly anionic acrylamide polymer, The purpose of the invention method, which is to improve filler retention, is not achieved at all and is meaningless. The paper manufacturing method of the present invention has the above-mentioned structure, and produces a neutral or weakly alkaline aqueous pulp slurry in which sulfuric acid is not used at all, or even if it is used, the amount thereof is suppressed to a very small amount. In a paper manufacturing method comprising drying, a cationic polymer substance and an anionic acrylamide polymer having a molecular weight of 100,000 to 1,000,000 and having 25 to 60 mol% of anionic groups are used as a filler retention improver. It consists of using an aqueous pulp slurry, and the filler retention aid used here has a much lower molecular weight than the filler retention aid used in the conventional paper industry. Even at low filler retention levels, it has an extremely excellent filler retention effect, does not stain wires or blankets during the papermaking process, is easy to work with, and has a good texture for the resulting paper, and is reasonably priced. It also has functions and effects that can be used economically. The extremely good effect of improving filler retention exerted by the filler retention improver used in the method of the present invention is completely unexpected, and although the mechanism is not certain, it is believed that highly anionic This may be because the polymer chains of the acrylamide-based polymer form a complex with the cationic polymer substance in a sufficiently extended state, and this complex maximizes its adsorption ability and crosslinking effect on dispersed particles such as fillers. It is considered. Incidentally, the above speculation is
The combined use of two types of filler retention improvers used in the paper manufacturing method of the present invention is supported by the fact that the effect of improving filler retention is significantly reduced in the presence of a large amount of sulfate. In other words, in the so-called "neutral papermaking method", which is a neutral or weakly alkaline papermaking method, in which a shift from acidic papermaking methods has been attracting attention in the paper industry in recent years, the two types of filler retention improvers have excellent properties. The ability to improve yield is in line with the current trend towards neutral paper in the paper manufacturing industry, and it is clear that the paper manufacturing method of the present invention is extremely valuable. Hereinafter, specific examples of the paper manufacturing method of the present invention will be explained in Examples, and the filler retention rate of the obtained paper will be explained together with that of the paper obtained in a comparative example. Example 1 (Cationic polymeric substance) Commercially available cationically modified starch (trade name: Neoposiparin, manufactured by Matsutani Chemical Co., Ltd.) was previously steamed and dissolved in water, and used as a 0.5% aqueous solution. (Highly anionic acrylamide polymer) A highly anionic acrylamide polymer with an anionic group content of 30 mol% obtained by treating an aqueous solution of polyacrylamide with an average molecular weight of 350,000 with caustic potassium and partially hydrolyzing it. An aqueous solution of the polymer was used. Paper making method L-BKP (CSF400c.c.) 2% containing 1.2g
After adding a predetermined amount of the above highly anionic acrylamide polymer solution to the aqueous pulp slurry and stirring thoroughly, add the same predetermined amount of the above cationic polymer substance aqueous solution, 0.2% sulfuric acid band,
An aqueous pulp slurry with a pH of 8.6 prepared by successively adding 35% of heavy calcium carbonate filler (both based on the absolute dry weight of the pulp) with sufficient stirring was hand-sheeted using a TAPPI standard sheet machine in the usual manner. The obtained wet paper was dehydrated by pressing at 3.5 Kg/cm ² pressure for 5 minutes, and then dried with a steam dryer (1.5 Kg/cm ² vapor pressure). The resulting handmade paper was conditioned for 24 hours at a humidity of 65%, and the paper weight was measured to calculate the basis weight. Next, the handmade paper was ashed according to a conventional method, and the yield rate (%) of the calcium carbonate filler was calculated from the results of the ash content measurement. The above results are shown in Table 1. Example 2 (Cationic polymeric substance) The same aqueous solution of cationically modified starch as in Example 1 was used. (Highly anionic acrylamide-based polymer) Anionic group content 60 mol obtained by treating the same polyacrylamide aqueous solution (average molecular weight 350,000) used in Example 1 with caustic potassium and partially hydrolyzing it. % of highly anionic acrylamide-based polymer was used. Paper making method The same method as in Example 1 was used. The results are shown in Table 1. Comparative Example 1 (Cationic polymeric substance) The same aqueous solution of cationically modified starch as in Example 1 was used. (Anionic acrylamide polymer) Anionic group content 10 mol% obtained by treating the same polyacrylamide aqueous solution (average molecular weight 350,000) as used in Example 1 with caustic potassium and partially hydrolyzing it. An aqueous solution of anionic acrylamide polymer was used. Paper making method The same method as in Example 1 was used. The results are shown in Table 1. Comparative Example 2 2% containing 1.2g of L-BKP (CSF400c.c.)
To each of the aqueous pulp slurries, 0.2% by weight of the three types of anionic acrylamide polymers used in Example 1, Example 2, and Comparative Example 1 were added and thoroughly stirred. Quality calcium carbonate filler 35% (both based on absolute dry weight of pulp)
A pulp slurry prepared by successively adding the following with sufficient stirring was hand-sheeted using a TAPPI standard sheet machine in the usual manner. The retention rate of calcium carbonate filler in the handmade paper was then measured in the same manner as in Example 1, and the results are shown in Table 1. Comparative Example 3 Handmade paper was obtained in the same manner as in Example 1, except that the addition of the highly anionic acrylamide polymer solution in Example 1 was omitted. Table 1 shows the results of measuring the retention rate of calcium carbonate filler in the handmade paper. Example 3 (Cationic polymer substance) An aqueous solution of a cationic acrylamide polymer (concentration 7%; viscosity
120 cps/25°C; cationic group content 20 mol% determined by colloid titration). (Highly anionic acrylamide polymer) A highly anionic acrylamide polymer with an anionic group content of 25 mol% obtained by treating an aqueous solution of polyacrylamide with an average molecular weight of 350,000 with caustic potassium and partially hydrolyzing it. An aqueous solution of the polymer was used. Paper making method L-BKP (CSF400c.c.) 2% containing 1.2g
Aqueous pulp slurry, a predetermined amount of the above highly anionic acrylamide polymer solution, a predetermined amount of the above cationic acrylamide polymer solution, 0.2% sulfuric acid band, and 35% heavy calcium carbonate filler (both based on absolute dry weight of pulp) ) was successively added with sufficient stirring to prepare an aqueous pulp slurry with a pH of 8.5, and a hand-made paper was prepared in the same manner as in Example 1 below. The test results of the obtained handmade paper are shown in Table 2. Example 4 (Cationic polymer substance) The same cationic acrylamide polymer aqueous solution as in Example 3 was used. (Highly anionic acrylamide polymer) An aqueous solution (concentration 10%; viscosity 1100 cps/25°C) of a copolymer of 50 mol% acrylamide and 50 mol% ammonium acrylate was used. Paper making method The same method as in Example 3 was used. The results are shown in Table 2. Comparative Example 4 (Cationic polymer substance) The same cationic acrylamide polymer aqueous solution as in Example 3 was used. (Anionic acrylamide polymer) 85 mol% acrylamide and potassium acrylate
Aqueous solution using copolymer with 15 mol% (concentration 10
%; viscosity 1150 cps/25°C) was used. Paper making method The same method as in Example 3 was used. The results are shown in Table 2. Comparative Example 5 A hand-made paper was obtained by using the same solution as the anionic acrylamide polymer aqueous solution used in Comparative Example 4 as a filler retention improver, and using the same conditions as the paper-making method of Example 3. Ta. The test results of the obtained handmade paper are shown in Table 2. Comparative Example 6 The same solution as the aqueous solution of the cationic acrylamide polymer used in Comparative Example 4 was used as a filler retention improver, and the other conditions were the same as those of Example 3 to make paper by hand. Obtained. The test results of the obtained handmade paper are shown in Table 2. Example 5 (Cationic polymer substance) Aqueous solution (concentration
10.4%; viscosity 11500 cps/25°C) was used. (Highly anionic acrylamide-based polymer) The same aqueous solution of the highly anionic acrylamide-based polymer (anionic group content: 30 mol %) as in Example 1 was used. Paper making method L/N=80/20 mixed BKP (CSF360c.c.) 1.2
After adding and mixing a predetermined amount of the above cationic polymer aqueous solution to a 2% aqueous pulp slurry containing g, a predetermined amount of the above highly anionic acrylamide polymer aqueous solution and 0.2 sulfate band were added.
% and a heavy calcium carbonate filler of 35% (both based on the absolute dry weight of the pulp) were sequentially added with sufficient stirring to prepare an aqueous pulp slurry with a pH of 8.5. A handmade paper was prepared according to the procedure. The test results of the obtained handmade paper are shown in Table 3. Example 6 (Cationic polymer substance) The same copolymer aqueous solution as in Example 5 was used. (Highly anionic acrylamide polymer) The same highly anionic acrylamide polymer aqueous solution as in Example 2 was used. Paper making method The same method as in Example 5 was used. The results are shown in Table 3. Comparative Example 7 (Cationic polymer substance) The same copolymer aqueous solution as in Example 5 was used. (Anionic acrylamide polymer) The same aqueous solution of anionic acrylamide polymer as in Comparative Example 1 was used. Paper making method The same method as in Example 5 was used. The results are shown in Table 3. Comparative Example 8 The same solution as the aqueous solution of the cationic acrylamide polymer used in Comparative Example 7 was used as a filler retention improver, and the other conditions were the same as the paper making method of Example 5 to make paper by hand. Obtained. Table 3 shows the test results for the handmade paper obtained. Comparative Example 10 (Cationic acrylamide polymer) The same copolymer aqueous solution as in Example 5 was used. (Anionic acrylamide polymer) Anionic group content 20 mol% obtained by treating the same polyacrylamide aqueous solution (average molecular weight 350,000) as used in Example 1 with caustic potassium and partially hydrolyzing it. An aqueous solution of a highly anionic acrylamide polymer was used. Paper making method The same method as in Example 5 was used. The results are shown in Table 3. Comparative Example 11 (Cationic acrylamide polymer) The same copolymer aqueous solution as in Example 5 was used. (Anionic acrylamide polymer) Anionic group content 65 mol% obtained by treating the same polyacrylamide aqueous solution (average molecular weight 350,000) as used in Example 1 with caustic potassium and partially hydrolyzing it. An aqueous solution of a highly anionic acrylamide polymer was used. Paper making method The same method as in Example 5 was used. The results are shown in Table 3. Example 7 (Cationic polymer substance) The same aqueous solution of cationic acrylamide polymer as in Example 3 was used. (Highly anionic acrylamide polymer) The same highly anionic acrylamide polymer aqueous solution as in Example 1 was used. Paper making method To an aqueous pulp slurry containing 1.2 g of L-BKP (CSF430c.c.), a predetermined amount of the aqueous solution of the highly anionic acrylamide polymer, a predetermined amount of the aqueous solution of the cationic acrylamide polymer, and sulfuric acid band were added. An aqueous pulp slurry prepared by sequentially adding a predetermined amount of a commercially available alkyl ketene dimer sizing agent 0.15% and a heavy calcium carbonate filler 30% (both based on the absolute dry weight of the pulp) with sufficient stirring, Thereafter, paper was made in the same manner as in Example 1 to prepare handmade paper. Table 4 shows the test results of the obtained handmade paper. Example 8 (Cationic polymer substance) The same aqueous solution of cationic acrylamide polymer as in Example 3 was used. (Highly anionic acrylamide-based polymer) The same highly anionic acrylamide-based polymer aqueous solution as in Example 2 was used. Paper making method The same method as in Example 7 was used. The results are shown in Table 4. Comparative Example 9 (Cationic polymer substance) The same aqueous solution of cationic acrylamide polymer as in Example 3 was used. (Anionic acrylamide polymer) The same aqueous solution of anionic acrylamide polymer as in Comparative Example 1 was used. Paper making method The same method as in Example 7 was used. The results are shown in Table 4. The anionic PAM shown in Tables 1 to 4 below refers to an acrylamide-based polymer having an anionic group, and the amount (%) of each component is expressed as % by absolute dry weight of the pulp. It is about.

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Claims (1)

[Scope of Claims] 1. A paper manufacturing method for forming and drying a neutral or weakly alkaline aqueous pulp slurry containing a filler, comprising a cationic polymeric substance and a molecular weight 10 containing 25 to 60 mol% of anionic groups. A papermaking method characterized by using an aqueous pulp slurry containing a highly anionic acrylamide polymer of 1,000 to 1,000,000. 2 The cationic polymer substance has a molecular weight of 10,000 to 100
The paper manufacturing method according to claim 1, wherein the cationic acrylamide polymer is used.