KR19980023055A - Preparation method of zwitterion latex - Google Patents

Abstract

The present invention relates to a method for producing amphoteric latex using an amphoteric surfactant having an anionic (-) carboxyl group and a cationic (+) amine at the same time.

Zwitterion latex is prepared by dividing into the initial polymerization stage and the growth polymerization stage, the weight ratio of the monomer to be added to the initial polymerization stage and the growth polymerization stage is 20 ~ 30/70 ~ 80, and 0.5 ~ 1.5 weight of emulsifier in the initial polymerization stage In the addition, 0.1 ~ 0.14 parts by weight in the growth polymerization step was added to increase the polymerization temperature stepwise 60 ℃ → 70 ℃ → 75 ℃ → 80 ℃ to complete the polymerization to prepare a zwitterion latex.

The coated paper using the zwitterionic latex prepared as described above is bulky and porous due to the suppression of binder movement to the surface of the coating layer and penetration into the base paper by the electrostatic interaction of pigment, latex, and latex and fiberization of the base surface. As the coated layer is formed, the air permeability increases, and various ink repairability and ink setability are improved, so that the printing titration is excellent.

Description

Preparation method of zwitterion latex

The present invention relates to a method for producing amphoteric latex using an amphoteric surfactant having an anionic (-) carboxyl group and a cationic (+) amine at the same time.

Coating liquids consist of various additives such as pigments, latexes, and water-soluble polymers, of which latex is used for the purpose of adhering pigment particles, which are the main components of coating liquids, and fixing pigment particles to the surface of the base paper. Such latex is finally bonded to the pigment and the contact point of the pigment or pigment and the contact point between the pigment and the base paper while the coating solution is dried to serve as a binder. In this process, however, the latex in the coating liquid moves to the surface of the coating layer and the base paper together with the water molecules by forced drying and dehydration in the paper direction, resulting in uneven distribution of the binder in the coating layer. It can also cause migration.

Conventional anionic latexes have hydrophilic groups such as sulfonic acid groups (-SO ₃ H) or carboxyl groups (-COOH) on the particle surface to increase the stability, adhesion, dispersibility and fluidity of the latex, but the phenomenon of binder movement occurs easily. Due to such a binder movement, a non-uniform film is formed and the printing ink is not evenly printed when printing coated paper, and the water-resistant adhesive strength is low due to the high hygroscopic alkali (NaOH) and KOH properties after the film is formed. Since the water-repellent agent (劑 水 和 劑) must be added together when dispersing the pigment, the viscosity of the pigment dispersion is increased due to the influence of the added water-resistant agent has a problem that the fluidity is lowered. On the other hand, there is a method of using a cationic color system as a method of suppressing the binder movement, but problems such as the use of expensive dispersant and difficult to control workability at high speed coating because the whole system is cationic Is being pointed out.

The present invention solves the binder migration phenomenon, which is the biggest problem in paper coating, and is able to adjust the surface charge of latex by pH as a new method that can take advantage of the anionic color system method. An amphoteric latex was invented and completed. In other words, in the form of positive ions (+,-) on the surface of the particles, they become anionic by dissociation of carboxyl groups under alkaline conditions and disperse well with clays having negative (-) charges. It becomes cationic by dissociation of and binds to the surface of clay particles electrostatically. Therefore, when applied, the pH decreases during the drying process, and it combines with clay particles to form a bulky coating layer. Since it is strongly adsorbed, penetration into the base paper is suppressed, so that no binder movement occurs.

Therefore, in coating workability, it is the same as the coating solution of the anionic latex system conventionally used, and after apply | coating to a base paper, it is characterized by the characteristic of a cationic (+) color system.

1 is a diagram showing the morphological differences between the coating layer using anionic latex and zwitterionic latex, when the zwitterionic emulsifier is used, the coating layer is caused by the electrostatic interaction of pigments with latex, latex and fibers on the base surface. The binder movement to the surface and the penetration into the base paper are suppressed, indicating that a large coating layer is formed at the same coating amount.

* Explanation of symbols for main parts of the drawings

1: base layer, 2: coating layer, 3: latex particles, 4: pigment

Cationic ion latex is prepared by dividing into initial polymerization stage and growth polymerization stage. The weight ratio of monomers to be added to the initial polymerization stage and the growth polymerization stage is 20 to 30/70 to 80, and 0.15 to 0.25 parts by weight of the emulsifier in the initial polymerization stage. In the addition, 0.9-1.1 parts by weight in the propagation polymerization step was completed while the polymerization temperature was gradually raised to 60 ℃ → 70 ℃ → 75 ℃ → 80 ℃ to prepare a zwitterion latex.

In the initial polymerization stage, 5.0 to 7.0 parts by weight of butadiene monomer, 11.026 to 13.026 parts by weight of styrene monomer, 2.474 to 4.474 parts by weight of methyl methacrylate monomer, 1.0 to 2.0 parts by weight of potassium persulfate as initiator and 0.5 to emulsifier in a 2 L reactor. 1.5 parts by weight, itaconic acid monomers 2.0. To 4.0 parts by weight, acrylic acid monomers 0.4 to 0.6 parts by weight, 0.0665 to 0.0865 parts by weight of a chain transfer agent, 0.0665 to 0.0865 parts by weight of ion exchanged water, and 147.3 parts by weight of ion-exchanged water, After free emulsion, the mixture was heated to 60 ° C and 0.4 to 0.6 parts by weight of sodium bisulfate, a reducing agent, was reacted for 2 hours. Here, the emulsifier may be N, N-dimethyl-n-laurylbetaine, which is a zwitterionic emulsifier, or a mixture with sodium dodecylbenzenesulfonate, an anionic emulsifier.

In the propagation polymerization step, 30.0 to 34.0 parts by weight of butadiene monomer, 30.974 to 34.974 parts by weight of styrene monomer, 8.526 to 10.526 methylmethacrylate monomer, 0.448 to 0.648 part by weight of tertiary-dodecylmercaptan, 0.1 to 0.14 parts by weight of an emulsifier, 0.4 to 0.6 parts by weight of an acrylic acid monomer, and 7.2 parts by weight of ion-exchanged water are continuously charged over 8 hours. At this time, the polymerization temperature was started at 70 ℃ and after 4 hours the temperature was raised to 75 ℃ to react. Here, as the emulsifier, N, N-dimethyl-n-laurylbetaine, which is a zwitterionic emulsifier, alone or a mixture with sodium dodecylbenzenesulfonate, an anionic emulsifier, was used. 0.22 and 0.1 weight part respectively, and 0.5 weight part is added after 8 hours of acrylic acid. In this polymerization step, the emulsifier and acrylic acid are prepared in 10% aqueous solution, and itaconic acid is prepared in 3% aqueous solution, regardless of whether it is an initial polymerization stage or a growth polymerization stage. After the addition of reagents, the temperature was raised to 80 ° C., aged for 4 hours, 2.0 parts by weight of sodium hydroxide was added and stirred for about 30 minutes to prepare paper-based butadiene-styrene copolymer latex.

N, N-dimethyl-n-laurylbetaine (LNB; N, N-Dimethy1-n-Laurylbataine) used as the amphoteric surfactant in the present invention is 60 ml of water and sodium chloroacetate in 1 L flask After adding (sodium chloroacetate) and completely dissolving, acetone and dimethyl laurylamine were added in a 1: 1 molar ratio to sodium chloroacetate and reacted at a temperature of 80 to 85 ° C. for 5 hours. As shown in the chemical formula of having an acid and a base group in a molecule exists in the form of three ions depending on the pH of the aqueous solution.

[Formula]

Differences in Chemical Structure According to pH of Cationic Emulsifier

What is represented by the formula (2) below shows that the charge on the surface of the zwitterion latex is changed according to the pH compared to the anion latex.

[Formula 2]

Structural Differences Between Anionic and Cationic Latexes

The present invention will be described in more detail with reference to Examples and Comparative Examples, but the present invention is not limited to these Examples.

Comparative Example 1

Initial polymerization stage

Into the reactor of 2L capacity, the following polymerization reagent except for sodium bisulfate, which is a gardening agent, was added all at once, pre-emulsified at 40 ° C for 30 minutes, and then heated to 60 ° C and sodium bisulfate was started. do.

Butadiene 6.0 parts by weight

Styrene 12.026 parts by weight

Methyl methacrylate 3.474 parts by weight

Potassium Persulfate 1.0 parts by weight

Sodium dodecylbenzenesulfonate 1.0 parts by weight

Itaconic acid 3.0 parts by weight

0.5 parts by weight of acrylic acid

Tertiary-dodecyl mercaptan 0.0765 parts by weight

Sodium Bisulfate 0.5 part by weight

147.3 parts by weight of ion-exchanged water

The above polymerization mixture is reacted at 60 ° C for 2 hours.

Chinese polymerization stage

The following polymerization reagent was continuously added to the polymerization reaction produced in the initial polymerization stage over 8 hours. At this time, it started at the polymerization temperature of 70 ° C. and then increased to 75 ° C. after 4 hours.

Butadiene 32.0 parts by weight

Styrene 32.974 parts by weight

Methyl methacrylate 9.526 parts by weight

Tasheri-dodecyl mercaptan 0.548 parts by weight

Sodium dodecylbenzenesulfonate 0.12 parts by weight

0.5 parts by weight of acrylic acid

7.2 parts by weight of ion-exchanged water

Sodium dodecyl benzenesulfonate as an anionic emulsifier was added 0.02, 0.1 parts by weight and 4 hours after the start of the polymerization polymerization step and 0.5 parts by weight of acrylic acid after 8 hours. In this polymerization step, an emulsifier and acrylic acid are prepared in 10% aqueous solution, and itaconic acid in 3% aqueous solution.

After the addition of the reagents, the temperature was raised to 80 ° C., aged for 4 hours, 2.0 parts by weight of sodium hydroxide was added and stirred for about 30 minutes to complete the polymerization reaction.

Example 1

Initial polymerization stage

Into the reactor of 2L capacity, the following polymerization reagents except sodium bisulfate, which is a reducing agent, are collectively added, pre-emulsified at 40 ° C. for 30 minutes, then heated to 60 ° C. and simultaneously added with sodium bisulfate to start the reaction. do.

Butadiene 6.0 parts by weight

Styrene 12.026 parts by weight

Methyl methacrylate 3.474 parts by weight

Potassium Persulfate 1.0 parts by weight

Sodium dodecylbenzenesulfonate 0.75 parts by weight

0.25 parts by weight of N, N-dimethyl-n-laurylbetaine

Itaconic acid 3.0 parts by weight

0.5 parts by weight of acrylic acid

Tertiary-dodecyl mercaptan 0.0765 parts by weight

Sodium Bisulfate 0.5 part by weight

147.3 parts by weight of ion-exchanged water

The above polymerization mixture is reacted at 60 ° C for 2 hours.

Proliferation polymerization stage

The following polymerization reagent was continuously added to the polymerization reaction produced in the initial polymerization step over 8 hours. At this time, the polymerization temperature was started at 70 ℃ and after 4 hours the temperature was raised to 75 ℃ to react.

Butadiene 30.0 parts by weight

Styrene 30.974 parts by weight

Methyl methacrylate 8.526 parts by weight

Tertiary-dodecyl mercaptan 0.448 parts by weight

Sodium dodecylbenzenesulfonate 0.09 parts by weight

N, N-dimethyl-n-laurylbetaine 0.03 parts by weight

0.5 parts by weight of acrylic acid

7.2 parts by weight of ion-exchanged water

The emulsifier is a mixture of 0.09 parts by weight of sodium dodecylbenzenesulfonate and 0.03 parts by weight of N, N-dimethyl-n-lauribetaine, added 0.02 and 0.1 parts by weight, respectively, 4 hours after the start of the propagation polymerization step. 0.5 parts by weight is added after the time. In this polymerization step, an emulsifier and acrylic acid are prepared in 10% aqueous solution, and itaconic acid in 3% aqueous solution.

After the addition of the reagent, the temperature was raised to 80 ° C. and aged for 4 hours, 2.0 parts by weight of sodium hydroxide was added thereto, followed by stirring for about 30 minutes to complete the polymerization reaction.

Example 2

0.50 parts by weight of sodium dodecylbenzenesulfonate in the initial growth polymerization step, 0.50 parts by weight of N, N-dimethyl-n-laurylbetaine, 0.06 parts by weight of sodium dodecylbenzenesulfonate in the growth polymerization step, N, N It was prepared in the same manner as in Example 1 except that 0.06 parts by weight of -dimethyl-n-laurylbetaine was used.

Example 3

0.25 parts by weight of sodium dodecylbenzenesulfonate in the initial growth polymerization step, 0.75 parts by weight of N, N-dimethyl-n-laurylbetaine, 0.03 parts by weight of sodium dodecylbenzenesulfonate in the growth polymerization step, N, N It was prepared in the same manner as in Example 1 except that 0.09 parts by weight of -dimethyl-n-lauribetaine was used.

Example 4

Sodium dodecyl benzenesulfonate is not used in the initial growth polymerization step, N, N-dimethyl-n-lauribetaine 1.0 parts by weight is used, sodium dodecylbenzene sulfonane is not used in the growth polymerization step, N Was prepared in the same manner as in Example 1, except that 0.12 parts by weight of N-dimethyl-n-laurylbetaine was used.

For proper comparison of the zwitterion and the anion latex, the basic physical properties that can affect the final physical properties were prepared as shown in Table 1.

TABLE 1

Lacquer with the above basic properties was prepared in each of the coating colors according to the prescription shown in Table 2, and the coating amount was 12g / ㎡ using Rod Coating No. 12 as the paper coating color on the base paper. It coated to the extent. Immediately after coating, it was dried for 30 seconds in a hot air dryer at 150 ℃. After adjusting the humidity overnight at 20 ° C. and 65% relative humidity, the obtained coated paper was subjected to two supercalor treatments at 60 ° C. linear pressure of 50 kg / cm 2 to prepare a sample.

TABLE 2

The coated paper properties and printability test results of the coating solution prepared by dividing the positive ion latex and the anionic latex are shown in Table 3.

TABLE 3

The above properties were measured by the following method.

Opacity: Several samples were prepared for one sample using a Hanter colorimetric photometer, and each was measured and its average value was defined as the opacity value.

Air permeability: Using an Oken type air permeability tester, several samples were prepared for one sample, and each sample was measured to give an average value.

Dry pick: After printing 0.5 sec of ink on coated paper specimens using R1 printing tester type II, the degree of paper tearing was visually determined and scored by five-point method.

Wet pick: R1 printing tester type I was used to disperse 0.4cc of ink on the rubber roll, and then distribute water on the molton roll uniformly to the left and right to pick the state of picking It was visually judged and evaluated by the 5-point method.

· Adherence: 0.3cc of ink and Jerry Compound in a ratio of 8: 2 using R1 Printing Tester Type I. After injection into water tonton rolls, disperse and print on paper specimens. The ink landing property of the surface was determined by the 5-point method.

KN ink repairability: Measure the whiteness of coated paper using Hanter colorimetric photometer, apply the coated paper sample uniformly with KN ink, remove ink on the layer after 2 minutes and measure the whiteness. The whiteness fall rate before and after printing was calculated.

· Croda ink repairability: Measure the whiteness of coated paper by using Hanter colorimetric photometer, and then apply the coded ink uniformly to the coated paper specimen. After 1 minute, the ink was removed, the ink was wiped off uniformly with crawfish, and the whiteness reduction rate before and after printing was calculated.

Ink set: Print the coated paper specimen using 0.4cc of ink using the R1 printing tester type II, place a blank sheet on the printed specimen, and pressurize the pressure little by little every time. [Time is 45 Seconds (15 Seconds-15 Seconds-15 Seconds)] The judgment was made by the five-point method by peeling the blank paper and the ink copy state on the blank paper.

Coated paper using zwitterion latex had the following advantages compared to coated paper using anionic latex.

Opacity is not different, but air permeability is greatly improved.

Dry pick strength is slightly lower but wet pick strength is significantly improved.

Inverse correlation properties, wet pick strength and landing ability are improved at the same time.

* Excellent ink repair and high ink setability.

As described above, the coated paper using zwitterion latex suppresses binder movement to the surface of the coating layer and penetration into the base paper by electrostatic interaction of pigments with latex, latex and fibers on the base surface, thereby increasing volume and porosity. The coating layer is formed to increase the air permeability, and various ink repairability and ink setability are improved, thereby being excellent in printability. In conclusion, the latex prepared by using amphoteric emulsifier instead of the anionic emulsifier used by the same monomer ratio and the same manufacturing method gives good results in coating paper and printability, so that excellent latex can be obtained without increasing material cost or changing the manufacturing method. Could.

Claims (3)

In the method for producing butadiene-styrene copolymer latex for paper processing, the weight ratio of monomers to be added to the initial polymerization stage and the growth polymerization stage is 20 to 30/70 to 80, and 0.5 to 1.5 parts by weight of an emulsifier is added in the initial polymerization stage And 0.1 to 0.14 parts by weight in the propagation polymerization step, and the polymerization temperature is gradually raised from 60 ° C. to 70 ° C. to 75 ° C. to 80 ° C. to complete the polymerization. The method according to claim 1, wherein 5.0 to 7.0 parts by weight of butadiene monomer, 11.026 to 13.026 parts by weight of styrene monomer, 2.474 to 4.474 parts by weight of methyl methacrylate monomer, 1.0 to 2.0 parts by weight of potassium persulfate as an initiator, and an emulsifier 0.5 to 1.5 parts by weight of a mixture with N, N-dimethyl-n-laurylbetaine or sodium dodecylbenzenesulfonate, 2.0 to 4.0 parts by weight of itaconic acid monomer, 0.4 to 0.6 parts by weight of acrylic acid monomer, 0.4 parts of acrylic acid monomer To 0.6 parts by weight, 0.0665 to 0.0865 parts by weight of tertiary-dodecyl capcaptan, a chain transfer agent, 0.4 to 0.6 parts by weight of sodium bisulfate as a reducing agent, and 147.3 parts by weight of ion-exchanged water, and reacted for 2 hours. 30.0 to 34.0 parts by weight, styrene monomer 30.974 to 34.974 parts by weight, methyl methacrylate monomer 8.526 to 10.526 parts by weight, tertiary-dodecyl mercaptan 0.448 to 0.648 part by weight, emulsifier 0.1 to 0.14 part by weight The reaction was carried out continuously while adding 7.2 parts by weight of ion-exchanged water for 8 hours. Acrylic acid was added at 0.5 hours by the end of the growth polymerization step, and the emulsifier was started at the start of the growth polymerization step and 4 hours after the start of the polymerization polymerization step. 0.02, 0.1 parts by weight of 8 hours after the proliferation polymerization step after 4 hours of aging and sodium hydroxide 2.0 parts by weight to terminate the reaction to produce a zwitterion latex. The emulsifying agent according to claim 1 or 2, wherein the emulsifying agent is a zwitterionic by using N, N-dimethy-n-laurylbetaine which is a zwitterionic emulsifier alone, or a mixture with sodium dodecylbenzenesulfonate as an anionic emulsifier. How to make latex.