JP2000026530A - Polymer of cyclic amidine structure, production and use thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a polymer useful for fixing especially a dye, a pigment, etc., as a cationic water soluble polymer by including specific 2 kinds of amidine structures in high contents to make the reduced viscosity of the polymer a specific value. SOLUTION: This polymer having cyclic amidine structures having 0.01-10 dl/g, preferably 0.01-6 dl/g and more preferably 0.01-5 dl/g reduced viscosity (measured at 0.1 g/dl concentration in aqueous 1 N sodium chloride solution at 25 deg.C) is obtained by including a 5-membered cyclic amidine structure of formula I (X is a protonic acid) and a 6-membered amidine structure of formula II in total >=50 mol.%. It is preferable that the copolymer contains 5-99 mol.% structure of formula I and 1-90 mol.% structure of formula II. The polymer is obtained e.g. by a method, etc., for polymerizing a mixture containing N- vinylformamide and acrylonitrile in a molar ratio of (45:55)-(95:5) in the presence of a radical polymerization catalyst in an aqueous medium, then hydrolizing the obtained polymer, removing formic acid formed and heating.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a polymer having an amidine ring structure, a process for producing the polymer and its use. Specifically, the present invention relates to a polymer having a high content of a 5-membered or 6-membered amidine ring structure and effective for immobilizing various functional substances, particularly dyes and pigments.

[0002]

2. Description of the Related Art A polymer having a vinylamine unit as a repeating unit, such as a hydrolyzate of a polymer or copolymer of N-vinylformamide or N-vinylacetamide, is a cationic polymer having a reactive primary amino group. As a water-soluble polymer, functions of binding and fixing various functional substances are known, and various uses have been proposed. For example, Japanese Patent Laid-Open Publication No.
There has been proposed a recording sheet for an inkjet printer in which a film of a partial hydrolyzate of polyvinylformamide is formed on a transparent support.

[0003] However, there are drawbacks associated with the use of polyvinylamine or vinylamine copolymers. That is, since vinylamine is a weak base, its dissociation is suppressed particularly in a neutral region, and it is difficult to form an ion complex. Therefore, when an ink is fixed by forming a polyion complex and insolubilizing with water, as in the case of recording paper of an ink jet printer, the function may be reduced in some cases. As a method for improving this point, it is conceivable to increase the degree of dissociation by quaternizing the amino group.
However, since the cation density of polyvinylamine is high, it is difficult to increase the reaction rate when quaternizing.

As another improvement method, for example, Japanese Patent Application Laid-Open
This is an amidine-forming method described in, for example, 192513. That is, this is a method in which an adjacent amino group and a nitrile group of a copolymer hydrolyzate of N-vinylamide and acrylonitrile are reacted to introduce a 5-membered amidine ring structure. The amidine ring compound is effective as a dye fixing agent at the time of dyeing (JP-A-7-157515), or used as a paper surface coating agent for recording paper of an ink-jet printer (JP-A-Heisei 7-157515). 8-39927). JP-A-9-87323 discloses that a polymer having an N-vinylformamide unit and an N-vinylamine unit and a 6-membered amidine ring structure introduced therein is suitable as a dye fixing agent and a papermaking additive. It is described. However, the polymers disclosed therein have room for further improvement in performance.

[0005]

SUMMARY OF THE INVENTION In view of the above circumstances, an object of the present invention is to provide a new polymer useful as a cationic water-soluble polymer for various uses.

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, have found that acrylonitrile
By introducing a 5-membered ring amidine structure and a 6-membered ring amidine structure into an N-vinylformamide copolymer, it has been found that the performance can be further improved as a polycation, and the present invention has been achieved. That is, the gist of the present invention is to provide a 5-membered cyclic amidine structure represented by the following formula (1) and a 6-membered cyclic amidine structure represented by the following formula (2), The content is 50 mol% or more in total, and the value of the reduced viscosity measured at 25 ° C. as a 0.1 g / dl solution in 1 N saline is 0.01 to 1
0 dl / g.

[0007]

Embedded image (Wherein X represents a protonic acid) The present invention will be described in detail below.

The polymer having a 5- or 6-membered amidine structure according to the present invention is obtained, for example, from a copolymer of N-vinylformamide and acrylonitrile.
In this case, the 5- and 6-membered amidine rings are represented by the following formula (a)
And the mechanism shown in the conceptual diagram of equation (b).

[0009]

Embedded image

And

[0011]

Embedded image

As shown in the above conceptual diagram, it is considered that the 5-membered ring amidine has an amidine ring having the target structure represented by (1) or (1 ′), but (1) and (1 ′) indicate nuclear magnetic properties. In resonance analysis (NMR), infrared spectroscopy (IR), etc.,
In general, both of the structures of the 5-membered amidine are represented by the formula (1) in the present specification because they are observed equivalently. Regarding the six-membered amidine,
Similarly, it is considered that the structures (2) and (2 ′) exist, and both of them are represented by the formula (2). The mol% of the amidine ring in the polymer is obtained by analyzing the polymer by NMR and calculating the ratio of the amidine ring unit, with each unit constituting the polymer being 1 mol.

The reason why an amidine ring is preferable as a fixing agent for a dye or the like is that the degree of dissociation is higher than that of a vinylamine group. That is, in the vicinity of neutrality where the polymer is actually used, the amidine group is dissociated more than the amino group, and therefore, it is considered that the ability to substantially form a complex with the dye and fix it is high. Regarding this, in the above-mentioned JP-A-7-157515 and JP-A-8-39927, as a dye fixing agent or a surface treatment agent for an ink jet printer recording paper, the effect of a polymer containing no amidine ring is higher. It is also evident from the fact that is shown to be high.

By the way, both published patents indicate that amino groups present in the polymer are preferable because they function as cationic groups. However, when examined in more detail, as described above, the amidine ring structure is more preferable than the primary amino group because the dissociation property is more improved than the amino group. Further, the primary amino group has high reactivity and may undergo various reactions such as amidation and reduction. Therefore, depending on the type of the dye, the primary amino group may react with the remaining amino group to discolor the dye. In this respect, the amidine ring structure having less reactivity as described above than the amino group is preferable.

Further, the nitrile group has no ionic property and cannot be expected to have a fixing function. In addition, it is considered that the nitrile group may cause coloring or the like due to deterioration during heating. That is, the number of amino groups and nitrile groups is as small as possible and 5 to 6
Polymers rich in membered amidine groups are preferred. Further, the performance is further improved by converting the amino group into a more functional 6-membered ring amidine structure. There is no problem in performance even if the polymer is all a 6-membered ring amidine structure, but in consideration of cost, it is preferable to use acrylonitrile, which is a general-purpose monomer, and as a result, a 5-membered ring amidine structure is introduced. . Therefore, the polymer of the present invention has a 5-membered amidine structure of the formula (1) in an amount of 5 to 99 mol%, a 6-membered amidine structure of the formula (2) in an amount of 1 to 90 mol%, and preferably the formula (1) 25 to 70 mol%, the structure of the formula (2) 3 to 40 mol%, and the total amount of the amidine ring is 50 mol% or more, preferably 50 to 75 mol%.

[0016]

BEST MODE FOR CARRYING OUT THE INVENTION The polymer having an amidine structure used in the present invention is obtained from a copolymer of N-vinylformamide (abbreviated as NVF) and acrylonitrile (abbreviated as AN). In this case, the copolymerization ratio (molar ratio) of each monomer is NVF: AN = 45: 55 to 95: 5,
Preferably it is selected from the range of 45:55 to 70:30. The lower limit of N-vinylformamide is determined from the copolymerization curve. When the amount of N-vinylformamide is around 45 mol%, there is a point where the charged composition of the monomer and the constituent monomer composition of the produced copolymer are equal. It is desirable for the vinyl formamide monomer ratio to be higher than this. This is because the possibility that the acrylonitrile units are arranged side by side increases at a monomer ratio of less than this. That is, as shown in the conceptual diagram, when the NVF unit and the vinylamine unit derived from the NVF unit are arranged, a 6-membered ring amidine can be formed, and the vinylamine unit derived from the NVF unit and the AN unit are arranged side by side. If so, a 5-membered ring amidine can be formed. On the other hand, when the AN units are arranged side by side, no amidine ring is formed. Therefore, it is as much as possible to avoid the arrangement of acrylonitriles.

The upper limit of NVF may be substantially 100. In this case, in order to prevent the remaining amino groups from remaining, the hydrolysis rate of the polymer must be reduced, and N-vinylformamide must be used. Is selected in consideration of the fact that it is more expensive than acrylonitrile and is disadvantageous in terms of cost. As long as the resulting polymer has a total of 50 mol% or more of a 5-membered and 6-membered amidine structure and is water-soluble, other monomers are added and co-polymerized. It may be polymerized.

[0018] The polymerization method of N-vinylformamide and acrylonitrile is not particularly limited.
A radical polymerization method using a radical initiator is employed. As the initiator, a commonly used initiator such as a peroxide such as benzoyl peroxide or an azo compound may be used. However, an azo-based initiator is preferable since there is no change in pH due to acid generation during polymerization. Specifically, hydrochloride and acetate of 2,2'-azobis-4-amidinopropane, 4,4'-azobis-
Sodium salt of 4-cyanovaleric acid, azobis-N, N '
-Dimethyleneisobutylamidine hydrochloride and sulfate. The use amount of these polymerization initiators is usually 0.01 to 10% by weight based on the monomer, and may be added as needed to increase the polymerization reaction rate or adjust the molecular weight of the polymer. .

Various polymerization methods such as bulk polymerization, solution polymerization, precipitation polymerization from a solution, inverse suspension polymerization of an aqueous monomer solution, and emulsion polymerization can be employed. Thus, the polymerization in an aqueous solution is preferable since hydrolysis, deformic acid treatment, amidine treatment and the like can be continuously carried out in the same system. After the completion of the polymerization reaction, the obtained polymer is hydrolyzed to convert a part of the vinylamide group derived from the NVF unit into an amino group. The hydrolysis is performed under acidic conditions. The acid is preferably a monovalent strong acid. This is because the hydrolysis rate is slow unless it is a strong acid, and the use of a polyvalent acid may cause insolubilization of the cationic polymer by ionic crosslinking. Specifically, hydrochloric acid, nitric acid, p-toluenesulfonic acid, methanesulfonic acid, trifluoroacetic acid and the like are exemplified, and hydrochloric acid is particularly preferred.

The hydrolysis reaction is carried out by dissolving or suspending the polymer in an aqueous medium and adding the above-mentioned acid. The higher the reaction temperature, the faster the reaction, usually 50 to 12
0 ° C. The amount of the acid to be used is 0.1 to 3 equivalents to the NVF unit (when a monovalent acid is used, NV
1 mole of acid is 1 equivalent to 1 mole of F). Although the hydrolysis rate of the NVF unit and the amidine ring formation rate have a proportional relationship to some extent, if the hydrolysis rate is too high, the formyl groups decrease and the remaining amino groups that cannot form a 6-membered ring amidine increase, which is not preferable. . On the other hand, when the amount of the acid is too small, there is a problem that the hydrolysis rate is reduced.

After the vinylamide group is converted into a vinylamine group by hydrolysis, an amidine ring is formed. The amidine reaction is accelerated by heating. The heating may be performed after the hydrolysis or simultaneously with the hydrolysis. In addition, since the 6-membered ring amidination reaction is particularly faster in the neutral region than in the acidic region, the pH of the solution is raised to the neutral region to promote the amidation reaction. The means for raising the pH is not particularly limited, but a method of removing formic acid by-produced by hydrolysis is advantageous. That is, the vinylformamide group is converted into an amino group by hydrolysis, and formic acid is by-produced. Formic acid in the polymer is preferably removed because it reacts with a chemical substance such as a dye to cause discoloration, particularly when the polymer of the present invention is used as a fixing agent such as a dye. The removal method is not particularly limited, but during acid hydrolysis,
Formic acid can be converted to formate and removed by the presence of an alcohol under acidic conditions. In particular, by selecting an alcohol having a low boiling point such as methanol or ethanol as the alcohol, unreacted alcohol and the resulting formate can be easily distilled off. Removal of formic acid results in an increase in the pH of the solution and promotes the formation of 6-membered amidines. Further, by removing the formic acid, the secondary effects of reducing the coloring of the solution, lowering the solution viscosity and facilitating the handling can be obtained.

Specifically, an alcohol is added before the hydrolysis or during the reaction and heated to 40 to 120 ° C.
Formic acid is removed and the amidination reaction is carried out by distilling off the formed formate. The alcohol is preferably a C _{1 to} C ₄ monohydric alcohol, and particularly preferably methanol and ethanol. The addition amount is 0.5 to 1 per NVF unit.
The molar amount is preferably 0 times, and particularly preferably 1 to 5 times.

The polymer thus obtained is usually
It is provided in the form of an aqueous solution, but can be taken out as a powder or other forms using conventional means, if necessary. The polymer of the present invention has a reduced viscosity of 0.01 to 10 d measured at 25 ° C. as a 0.1 g / dl solution in 1 N saline.
1 / g, preferably 0.01 to 6 dl / g, more preferably 0.01 to 5 dl / g. Further, the polymer of the present invention has, in addition to the amidine ring represented by the formulas (1) and (2), about 0 to 10 mol% of the following repeating units.

[0024]

Embedded image

The polymer of the present invention has an action of immobilizing fine particles in a solution, and is used for applications such as an antistatic agent, a flocculant, a sludge treating agent, and a papermaking agent. It is useful as an antistatic agent for articles, a surface coating agent for printing media such as paper, and a fixing agent for dyes. For example, an aqueous solution of the polymer of the present invention is applied to the surface of a substrate such as paper, cloth, or film,
When printing is performed by an ink jet printer, the ink can be fixed well, and a recording medium having excellent water resistance and light resistance can be obtained. When used as a dye fixing agent, the dyed fiber is treated with the aqueous polymer solution of the present invention to fix the dye to the fiber, prevent color fading, and obtain a robust dyed product.

[0026]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples unless it exceeds the gist of the present invention. Examples 1 to 3 (1) Synthesis of N-vinylformamide / acrylonitrile copolymer In a 50 ml four-necked flask equipped with a stirrer, a nitrogen inlet tube, and a cooling tube, N-vinyl having a molar fraction shown in Table 1 was added. 6 g of a mixture of formamide and acrylonitrile, 24 g of demineralized water
And 0.45 g of polyethylene glycol (molecular weight 2)
10,000). The flask was heated to 70 ° C. while being stirred in a nitrogen gas stream, and a 10% by weight aqueous solution of 2,2′-azobis-2-amidinopropane hydrochloride was added to a 0.06% aqueous solution.
g was added to start the reaction. After another hour, 2,2'-
10% by weight of azobis-2-amidinopropane hydrochloride
0.03 g of an aqueous solution was added. 70 after stirring after addition of initiator
C. for 5 hours to obtain a suspension in which the polymer was precipitated in water.

(2) Modification of N-vinylformamide / acrylonitrile copolymer To the suspension obtained in (1), 0.65 equivalent of N-vinylformamide monomer to 35% hydrochloric acid was added. 1
After stirring for an hour, the temperature was raised to 90 ° C., and the mixture was stirred for 3 hours. Methanol was added 3 mole times the amount of N-vinylformamide monomer, and the mixture was further stirred at 90 ° C. for 3 hours, and then methanol and methyl formate were distilled off. Take a portion of the reaction mixture, ¹³
Table 1 shows the results of analyzing the structure by C-NMR and the results of measuring the reduced viscosity of a 0.1% by weight aqueous polymer solution (1N saline in 25 ° C.).

COMPARATIVE EXAMPLE 1 After polymerization in the same manner as in the Example, 0.65 equivalent of 35% hydrochloric acid with respect to N-vinylformamide monomer was added.
After stirring for an hour, the temperature was raised and the reaction was carried out at 90 ° C. for 3 hours. A part of the obtained polymer aqueous solution was taken, analyzed by ¹³ C-NMR, and the measurement result of the reduced viscosity is shown in Table 1.

Comparative Example 2 After polymerization in the same manner as in the Example, 1.05 equivalent of 35% hydrochloric acid to N-vinylformamide monomer was added, and the mixture was heated at 70 ° C. for 1 hour.
After stirring for an hour, the temperature was raised and the reaction was carried out at 90 ° C. for 3 hours. A part of the obtained polymer aqueous solution was taken, analyzed by ¹³ C-NMR, and the measurement result of the reduced viscosity is shown in Table 1.

[0030]

[Table 1]

Abbreviations NVF: N-vinylformamide (or N-vinylformamide unit) AN: Acrylonitrile (or acrylonitrile unit) VAM: Vinylamine unit 5AMZ: 5-membered amidine unit 6AMZ: 6-membered amidine unit Others: (7) A) a mixture of units of (9)

[0032]

Embedded image

Example 4 (Use for Inkjet Recording Sheet) A coating solution using the polymer obtained in Examples 1 to 3 and Comparative Examples 1 and 2 was applied to paper, and subjected to inkjet printing to obtain a test piece. And a water resistance test and a light resistance test were performed. Coating liquid composition: 5 g of silica gel (Finesil-X-37: manufactured by Tokuyama Soda Co., Ltd.), 20 g of a 10% aqueous solution of polyvinyl alcohol (Poval PVA117: manufactured by Kuraray Co., Ltd.) and 0.5 g of polymer solution of Examples and Comparative Examples (solid content) ) Was mixed to obtain a 12.5% solids aqueous solution using distilled water. Coating conditions: No. on plain paper After applying the coating solution with a 20 bar coater, the coating solution was dried at 100 ° C. for 7 minutes, left standing overnight in a constant temperature room at 23 ° C./65% humidity, and then printed. Printing: Solid printing was performed for each color of magenta, cyan, yellow, and black by an inkjet printer (manufactured by Canon Inc.). Water Resistance Test The printed test piece was immersed in distilled water (normal temperature) for 1 minute, dried, and then visually inspected for residual ink remaining on the printed portion according to the following criteria. The results are shown in Table-2. ◎: No bleeding and no color fading ：: Slight bleeding and no color bleeding Δ: Ink bleeds or partially flows. ×: Ink completely flows down.

[0034]

[Table 2]

Light Resistance Test The optical density (OD) of each color of the printed test piece was measured with an optical densitometer (Macbeth: RD920). O. M (black panel temperature 80
° C), the optical density of each color after irradiation for 80 hours was measured, and the light resistance was calculated by the following equation.

[0036]

## EQU1 ## Light resistance (%) = 100 × O. D. / O. D.

[0037]

[Table 3]

The polymer of the present invention has a great improvement effect on magenta dyes, which are particularly poor in light resistance.

Example 5 (Use as Dye Fixing Agent) (1) Evaluation of sweat fastness 4 g of each polymer obtained in Examples 1 to 3 and Comparative Example
An aqueous solution was prepared. Next, using this aqueous solution, a dyeing bath is prepared according to the following formulation (reactive dye concentration 5% (based on the weight of the fiber)). Heat treatment was performed.
The drawing ratio at that time was 70%. The dyes used were Kayashi On Red P-4BN and Kayashi On Turk P
-NGF (Nippon Kayaku Co., Ltd.). The dye bath formulation and the dyeing treatment conditions are as follows.

<Dye bath formulation> (g / l) Dye 100 Sodium alginate 0.5 Urea 100 Soda ash 15 Sodium metanitrobenzenesulfonate 5

<Processing Method> Processing is performed in the following order. Pad Dry (105 ℃ × 3min) Baking (160 ℃ × 2min) Soaping (90 ℃ × 5min)

Next, the sweat fastness of the treated dyed cloth was measured according to JIS.
It was evaluated by L-0848 (alkaline sweat method). The results are summarized in Table-4.

[0043]

[Table 4] A: Cotton-contaminated cloth B: Silk-contaminated cloth

(2) Evaluation of chlorine fastness 4 g / l of each polymer obtained in the above Examples and Comparative Examples
An aqueous solution was prepared. Next, a cotton cloth was immersed in the solution using the following reactive dye and dyed continuously, followed by mangle treatment and heat treatment at 150 ° C. for 90 seconds. The drawing ratio at that time was 70%. The dyes used were Cibacron Blue 3R (manufactured by Ciba Geigy) and Kayashion Gray P-NR (manufactured by Nippon Kayaku Co., Ltd.). The preparation of the dyeing bath and the dyeing treatment conditions are the same as in the case of the sweat fastness test. Next, the chlorine fastness of the treated dyed cloth was measured according to JIS.
It was evaluated by L-0884 (weak test and strong test). The results are shown in Table-5.

[0045]

[Table 5] A: Weak test B: Strong test

[0046]

As is evident from the examples, when applied to ink jet recording paper, the polymer solution of the present invention has less coloring of the coating film as compared with the conventional amidine ring-containing polymer solution, and It significantly improves light fastness, particularly to magenta dyes. Further, as a dye fixing agent for cotton cloth and silk cloth dyed with a reactive dye, the dyed cloth significantly improves the fastness against sweat and chlorine.

Continued on the front page (72) Inventor Yasuo Kitani 1, Toho-cho, Yokkaichi-shi, Mie, Mitsubishi Chemical Corporation Yokkaichi Office (72) Inventor Toshiya Seko 1, Toho-cho, Yokkaichi-shi, Mie Mitsubishi Yokkaichi Office F term (reference) 4J100 AM02Q AN04P BA13P CA04 CA31 DA09 HA08 HA45 HB25 HB44 HC27 HC71 JA13

Claims (5)

[Claims] 1. It has a 5-membered cyclic amidine structure represented by the following formula (1) and a 6-membered cyclic amidine structure represented by the following formula (2), and the content of these amidine ring structures in the polymer constitutional unit is: A weight of not less than 50 mol% in total and a reduced viscosity of 0.01 to 10 dl / g measured at 25 ° C. as a 0.1 g / dl solution in 1 N saline. Coalescing. Embedded image (Wherein, X represents a protonic acid) 2. The polymer according to claim 1, comprising 5 to 99 mol% of the amidine ring structure of the formula (1) and 1 to 90 mol% of the amidine structure of the formula (2). 3. N-vinylformamide to acrylonitrile in an aqueous medium in the presence of a radical polymerization catalyst.
2. The polymer according to claim 1, wherein after the monomer mixture containing a molar ratio of 5:55 to 95: 5 is polymerized, the mixture is hydrolyzed by adding an acid to remove generated formic acid and heated. Manufacturing method of coalescence. 4. A recording sheet for an ink jet printer obtained by applying an aqueous liquid containing the polymer according to claim 1 to a substrate. 5. A reactive dye fixing agent comprising the polymer according to claim 1.