Process for the production of paper sizing agents

Start of patent duration: 1980 05 15 Longest possible duration:

© Issued on: 1981 01 12 © inventor:

© Dependency: '© Pamphlets considered to delineate the state of the art:

DE-0S2400058

- 2 no. 360335

The invention relates to an improved process for the preparation of anionic sizing agents for paper based on maleic anhydride-diisobutylene copolymers.

From DE-OS 2361544 and 2501123 it is known to use largely alternating copolymers of maleic anhydride and diisobutylene for the production of extremely effective sizing 5 mittein for paper production. Thus, for example, according to DE-OS 2361544, the copolymerization of these monomers by free radicals in solvents such as aromatics, halogenated aromatics, ketones, esters of lower fatty acids, chlorinated aliphatic hydrocarbons or strongly polar solvents. Furthermore, it is described in DE-OS 2501123 that the copolymerization of the monomers in suspension using excess Diiso10 butylene as a dispersing medium in the presence of 0.5 to 10 wt .-%, based on maleic anhydride, of a soluble in the dispersing, special Dispersants can be carried out.

Despite the use of a large molar excess of diisobutylene, the copolymerization of these two monomers according to the described in the above-mentioned DE-OS process 15 does not lead to a complete Einpolymerisation of maleic anhydride, When isolating the maleic anhydride-diisobutylene copolymers as water-moist powders with a solids content> 80 Wt .-% loaded unreacted maleic anhydride as water-soluble maleic acid the filtrate during filtration or centrifugation in the sewage system. Due to a high COD or BOD value (.CSB = Chemical Oxygen Demand, BOD = Biological Oxygen Demand) of this wastewater as a result of maleic acid dissolved therein, its cleaning costs and thus also the costs increase.

The object of the invention was to modify the copolymerization of maleic anhydride and diisobutylene in solution and suspension in such a way that virtually complete copolymerization of the maleic anhydride present in the monomer mixture occurs.

The object was inventively achieved in that first the copolymerization of the monomers 25 maleic anhydride and diisobutylene was carried out in the usual way by free-radical route, and then shortly before or after the end of the polymerization between 1 and 12 mol%, based on maleic anhydride, a monomer of the general formula

C = CH₂

Ri being

R

H, CH₃, G, H_s, -0R₂, -O-CO-CHa,

-O

-CH

-CH₂-OH or -CH₂0-C0-CH₃ is

Ri for H, CH₃ and

Rs are a linear or branched alkyl group having 1 to 4 carbon atoms, or mixtures of these monomers with each other were added to the polymerization batch.

The invention thus provides an improved process for the preparation of anionic

Sizing agents for paper, consisting of aqueous or aqueous-alcoholic alkali, amine or ammonium salt solutions of copolymers of maleic anhydride and diisobutylene, prepared in substantially equimolecular and prepared in solvents or in suspension, their anhydride groups with linear or branched aliphatic monoalcohols having 1 to 20 carbon atoms or were esterified with cycloaliphatic monoalcohols having 5 or 6 carbon atoms to 10 to 100 mol% to the corresponding half esters, which is characterized in that in the carried out in solvents or in suspension copolymerization of maleic anhydride and diisobutylene shortly before or after completion of the copolymerization a monomer of the general formula

- 3 Nr.360335

CHj

Rx wherein R and R₃ have the meaning indicated, or mixtures of these monomers with one another in amounts of between 1 and 12 mol%, based on maleic anhydride, are added to the polymerization batch.

The process according to the invention gives copolymers in which the incorporation of maleic anhydride is between 94.0 and 99.4 mol%, and frequently more than 96.0 mol%, based on the maleic anhydride used. In addition, the paper sizing agents prepared from these copolymers unexpectedly have a sizing effect which is increased by 10 to 25% compared to the paper sizing agents obtained on the basis of DE-OS 2361544 and DE-OS 2501123 on slightly pre-glued as well as unsized paper.

The addition of the third monomer or of the monomer mixtures takes place at a point in time at which the polymerization conversion, based on maleic anhydride, has reached a constant value. Shortly after the addition, the conversion of maleic anhydride increases again until it has reached a value between 94 and 99.4 mol%, depending on the polymerization conditions and the monomers or monomer mixture used. The addition of this monomer or the monomer mixture can be carried out either alone or together with free-radical-forming substances at temperatures between 30 and 200 ° C. The duration of the reaction of the polymerization mixtures with the third monomer or the monomer mixtures is between 1 and 10 h.

Suitable for reaction with the residual maleic anhydride are monomers of the general formula

<img file="AT360335B_D0001.tif" />

wherein R, R_x have the meaning given.

Examples include: ethylene, propylene, xsobutylene, styrene, α-methylstyrene, p-methylstyrene, vinyl acetate, allyl acetate, isobutyl vinyl ether, allyl alcohol and methallyl alcohol.

Preference is given to the α-olefins corresponding to the above formula, in particular styrene, α-methylstyrene and isobutylene.

If the addition of the third monomer or of the monomer mixtures does not take place shortly before or after the end of the copolymerization but already at the beginning, no or only a slight reduction in the unreacted maleic anhydride content is achieved.

These monomers are used either alone or in mixtures with one another in amounts of between 1 and 12 mol%, based on maleic anhydride, but preferably in amounts of between 5 and 10 mol%.

The copolymerization process is carried out until the addition of the further monomer or the monomer mixture in a known manner, as described for example in DE-OS 2361544 and DE-OS 2501123.

The determination of non-polymerized maleic anhydride can be carried out in various ways adapted to the respective copolymerization process. Thus, when carrying out the copolymerization in solvents such as toluene, the polymer solution is subjected to stripping with hot water at a reduced pressure. Under azeotropic distillation of the solvent 40, the copolymer precipitates as a fine white, suspended in water powder. After filtering off this powder and evaporating the filtrate to dryness saponified maleic anhydride remains as free maleic acid as a residue. The amount of maleic acid is determined gravimetrically according to its spectroscopic identification. If the copolymerization is carried out by the suspension method using excess diisobutylene as the dispersing medium, 4 no. 360335, the turnover determination is carried out by weighing the unpolymerized maleic anhydride. The isolation of the diisobutylene insoluble maleic anhydride is carried out from the freed by filtration of diisobutylene copolymer powder under vacuum

10,26 mbar) at temperatures between 80 and 120 ° C. In this case, the maleic anhydride sublimates out of the copolymer powder and precipitates as a solid product in a cold trap connected to the evacuation apparatus.

The polymeric products obtained by the described improved copolymerization processes can, after their reaction with alcohols to give half-esters in the form of their alkali metal, ammonium or amine salts, be used excellently as anionic paper sizing agents. Suitable for the preparation of the half esters are linear or branched aliphatic monoalcohols having 1 to 20 carbon atoms and cycloaliphatic alcohols having 5 to 6 carbon atoms, the anhydride groups present in the copolymers are thereby esterified to 10 to 100 mol% to the corresponding half esters ,

Examples 1 to 4: In a 40 l steel autoclave are presented:

<td>15</td><td>3,675</td><td>kg</td><td>maleic anhydride</td>

<td></td><td>5.625</td><td>kg</td><td>diisobutylene</td>

<td></td><td>5,100</td><td>kg</td><td>toluene</td>

After rinsing the autoclave with nitrogen and sealing, the temperature is raised to 75 ° C with stirring and then from an initiator solution consisting of 0.0785 kg 20 Azoisobuttersäuredinitril in 1.350 kg of toluene initially added 20 wt .-% quickly. The remainder of the initiator solution is metered in within 2 h. It is stirred for 6 h at 75 ° C and then 0.039 kg Azoisobuttersäuredinitril, dissolved in 0.675 kg of toluene, metered during 1/2 h. Subsequently, the temperature is raised to 85 ° C, stirred for 6 h, the temperature is raised to 95 ° C and stirred for a further 8 h. Thereafter, the following amounts of styrene are rapidly added together with 0.039 kg Azoiso25 buttersäuredinitril dissolved in 0.675 kg of toluene.

<td>example</td><td>1</td><td>2</td><td>3</td><td>4</td>

<td>Mole% styrene (based on ä 1 used MAH)</td><td>0</td><td>5.65</td><td>7.52</td><td>9.42</td>

a)

MAH = maleic anhydride

The mixture is stirred for 2 h at 95 ° C, then the temperature is raised to 105 ° C and held the polymerization 2 h at this temperature.

After cooling the polymer solutions to 80 ° C 0.5625 kg of isopropanol are added to 0.469 kg of toluene for conversion into the Halb30 ester and these solutions are stirred for 2 h at 80 ° C. Subsequently, by introducing the solutions into about 70 ° C hot water with simultaneous azeotropic distillation of toluene and diisobutylene precipitated the partially esterified copolymers as fine white powder. The resulting polymer suspensions are still 2 h at

Stirred 90 ° C and 465.5 to 492.1 mbar.

Afterwards, they are filtered off, the filtrates are evaporated and the ones consisting of maleic acid

Residues balanced.

- 5 No.360335

Results:

<td>example</td><td>1</td><td>2</td><td>3</td><td>4</td>

<td>Wt .-% maleic acid (based on used MAH)</td><td>5.86</td><td>1.33</td><td>1.26</td><td>0.72</td>

Comparative Examples IA to 4A:

It is shown from the following four comparative examples that an immediate addition of the third monomer (styrene in these examples) to the polymerization batch leads to only a slight reduction in the content of unpolymerized maleic anhydride compared with Examples 1 to 4. The polymerizations were carried out in the same manner as described in Examples 1 to 4, with the only difference that the styrene was present in the monomer mixture before the initiator addition.

<td>example No.</td><td>Mole% styrene (based on used MAR)</td><td>Wt. (Based</td><td>% Maleic acid on inserted MAH)</td>

<td>1 A</td><td>0.0</td><td></td><td>7.74</td>

<td>2 A</td><td>2.55</td><td></td><td>6.63</td>

<td>3 A</td><td>5.10</td><td></td><td>5.93</td>

<td>4 A</td><td>10.20</td><td></td><td>5.25</td>

Examples 5 to 8: The following mixture is placed in a 100 l steel autoclave:

12.250 kg of maleic anhydride

41,000 kg of diisobutylene

2.130 kg dispersant (copolymer of diisobutylene and dodecyl maleate (prepared according to DE-OS 25011331).

It is purged with nitrogen, the temperature raised to 75 ° C and stirred at 110 to 120 Umdr / min. After the autoclave is capped, a slight nitrogen blanket pressure is applied, and from a solution of 0.325 kg of t-butyl peroctoate in 2,500 kg of diisobutylene, first 25 wt% is added at once. Then, the internal temperature of the reaction vessel 20 is raised to 90 ° C within 1 h, and then metered the remaining 75 wt .-% of the initiator solution for 1 h. After completion of metering is stirred for 6 h at 90 ° C and then the following amounts of ap styrene are added together with a solution of 0.050 kg tert.Butylperoctoat, dissolved in 0.460 kg of diisobutylene, within 1 h:

<td>example</td><td>5</td><td>6</td><td>7</td><td>8th</td>

<td>Mol% styrene (based on MAH used)</td><td>0</td><td>3.26</td><td>6.52</td><td>9.80</td>

- 6 Nr, 360335

The mixture is stirred for 2 h at 90 ° C, cooled to room temperature and filtered off.

The filtered polymer powders are subjected to a vacuum treatment at temperatures between 30 and 120 ° C and at pressures between 15.9 and 0.26 mbar over a period of 28 h.

The maleic anhydride sublimating out of the polymer powder in this process is precipitated as a solid, crystalline substance IFp: 55 ° C.) at the cooled sites of the sublimation apparatus. The maleic anhydride is collected, weighed and its amount based on the maleic anhydride used for the copolymerization:

<td>example</td><td>5</td><td>6</td><td>7</td><td>8th</td>

<td>% By weight of maleic anhydride relative to the MAH used)</td><td>7.65</td><td>5.74</td><td>1.41</td><td>0.56</td>

According to Examples 1 to 4, the copolymers are converted by reaction with isopropanol 10 in the half esters.

Comparative Example 5A to 8A:

The following four comparative examples show that by immediate addition of the third monomer in these examples, styrene) to the polymerization batch is also observed in the suspension polymerization process compared to Examples 5 to 8 only a small reduction in non-polymerized maleic anhydride.

The polymerizations were carried out in the same manner as described in Examples 5 to 8, with the difference that the amounts of styrene added in each case were already present in the starting monomer mixture before the addition of the initiator.

<td>example No.</td><td>Mole% styrene I'm referring to inserted MAH)</td><td>Wt .-% maleic anhydride I based on used MAH)</td>

<td>5 A</td><td>0.0</td><td>7.65</td>

<td>6 A</td><td>4.25</td><td>7.27</td>

<td>7 A</td><td>8.50</td><td>5.79</td>

<td>'8 A</td><td>12.75</td><td>5.65</td>

Examples 9 to 20: The following twelve examples were carried out by the suspension method analogous to Examples 5 to 8 using alkyl alcohol, methallyl alcohol and isobutylene instead of styrene.

Again, with increasing amounts of added at the end of the copolymerizations of maleic anhydride and diisobutylene monomers methallyl alcohol, allyl alcohol 25 and isobutylene over the carried out without the addition of third monomers copolymerization clear decreases in the amounts of non-polymerized maleic anhydride.

- 7 Nr.360335

<td>example No.</td><td>additional monomeric</td><td>Mol% additional monomeric (based on used MAH)</td><td>% By weight of maleic anhydride (based on the MAH used)</td>

<td>9</td><td>-</td><td>0.0</td><td>7.54</td>

<td>10</td><td>methallyl</td><td>5.14</td><td>3.42</td>

<td>11</td><td>methallyl</td><td>6.0</td><td>2.80</td>

<td>12</td><td>methallyl</td><td>8.0</td><td>2.61</td>

<td>13</td><td>methallyl</td><td>10.0</td><td>2.60</td>

<td>14</td><td>allyl alcohol</td><td>4.0</td><td>5.88</td>

<td>15</td><td>allyl alcohol</td><td>6.0</td><td>5.14</td>

<td>16</td><td>allyl alcohol</td><td>8.0</td><td>4.16</td>

<td>17</td><td>allyl alcohol</td><td>10.0</td><td>3.76</td>

<td>18</td><td>isobutylene</td><td>4.1</td><td>5.55</td>

<td>19</td><td>isobutylene</td><td>8.2</td><td>4.08</td>

<td>20</td><td>isobutylene</td><td>12.0</td><td>3.42</td>

To prepare the sizing agents, the copolymers according to Examples 1 to 4 can be converted into the half esters by reaction with isopropanol.

applications

The following four application examples show the utility of the partially esterified copolymers described in Examples 1 to 8 as sizing agents for paper in comparison to a copolymer prepared without addition of a third monomer.

For this purpose, various base papers were treated with the aqueous-ammoniacal solutions of these products on a laboratory size press from Mathis, Zurich, Switzerland, Type HF.

The sizing liquor for surface sizing was a solution of 5% by weight starch and

0.04 to 0.13% by weight of the sizing agent to be tested (calculated as 100% active substance) in 94.96 to 94.87% by weight of water.

The surface-sized papers were dried on a drying cylinder within 1 min at about 100 ° C. Before the sizing test, the papers were conditioned for 2 hours at room temperature.

The degree of sizing of the treated papers against ink was measured with the Hercules Sizing Tester according to the instruction manual of the manufacturer Hercules Inc., Wilmington, Delaware,

USA, measured. It records the time in seconds that passes to the remission drop to 65% of the remission value of paper when the test ink is applied to the paper and breaks through the paper. The test ink is the green test ink of the

Fa. Hercules used.

- 8 No. 363355

To determine the water absorption, sections of the treated papers were pre-weighed, immersed in water at 20 ° C for min, once pressed between filter paper by means of a 10 kg roll weight and weighed back. From the weight difference, the value for the bilateral water absorption in g / cm² calculated. The lower the water absorption, the better the effect of the tested sizing agent.

The percentages given in the tables refer to the proportion of sizing agent contained in the liquor, calculated as 100% active substance.

Application example 1

Here, a sizing agent was used, which was prepared from a copolymer of Examples 10 1 to 8 with the addition of 4.60 mol% of styrene, based on maleic anhydride.

This product was tested on pre-glued and unsized paper.

The unsized paper containing 12% talcum ash was made from bleached pulp with the addition of alum.

The used pre-glued paper with a content of 7% China Clay Ash was made from yellow! Pulp with the addition of about 0.1% conventional Harzleim lAbietinat basis) and alum produced.

The degree of sizing was measured with the Hercules Sizing Tester with a decrease of remission values ​​to 75%.

a) unsized paper:

<td rowspan="2"></td><td colspan="2">Sizing degree after Hercules in s at one Addition of</td>

<td colspan="2">0.09% | 0.13% Sizing agent (100%) to the fleet</td>

<td>With sizing agent 4.60 mole% styrene Sizing agent without styrene</td><td>422 331</td><td>526 419</td>

b) before sized paper:

<td rowspan="2"></td><td colspan="2">Sizing degree after Hercules in s at one Addition of</td>

<td colspan="2">0.09% | 0.13% Sizing agent (100%) to the fleet</td>

<td>With sizing agent 4.60 mole% styrene Sizing agent without styrene</td><td>236 112</td><td>440 219</td>

The examples show that the sizing agent obtainable according to the invention with a content of 4.60 mol% of styrene, based on maleic anhydride, gives the examined papers a significantly higher degree of sizing than the comparative product.

Application Example 2:

Here, a sizing agent was used, which was prepared from a copolymer according to Example 7 (6.52 moles of styrene). The sizing degree was measured with the Hercules Sizing Tester at a

Waste of remission values ​​measured at 65%.

Nr.360335

- 9 The paper used was an unsized paper as already described in application example 1a.

<td rowspan="2"></td><td colspan="2">Sizing degree after Hercules in s at one Addition of</td>

<td colspan="2">0.09% | 0.13% Sizing agent (100%) to the fleet</td>

<td>With sizing agent 6.52 mole% styrene Sizing agent without styrene</td><td>108 30</td><td>203 128</td>

Also from this example, a significant improvement in the sizing effect of the sizing agent obtainable according to the invention is evident in comparison to the comparative product.

Application Example 3

Here, a sizing agent was used, which was prepared from a copolymer according to Example 8 (9.80 mol% styrene). This product was tested on an unsized alum-containing paper (Example 3a) and on a paper glued with resin glue (Application Example 3b).

As a measure of the sizing effect of the tested products, the water absorption of the papers at various application rates was determined in these examples.

a) unsized paper:

<td rowspan="2"></td><td colspan="4">Water absorption in g / m^z with the addition of</td>

<td colspan="4">0.04% | 0.05% | 0.06% | 0.08% Sizing agent (100%) to the fleet</td>

<td>With sizing agent 9.80 mole% styrene Sizing agent without styrene</td><td>35.5 39.1</td><td>34.1 38.0</td><td>33.2 35.9</td><td>30.7 32.8</td>

b) before sized paper:

<td rowspan="2"></td><td colspan="3">Water absorption in g / m² with the addition of</td>

<td>0.04% j 0.05% Sizing agent ('</td><td>0.06% j , 00%) to the fleet</td><td>0.08%</td>

<td>With sizing agent 9.80 mole% styrene</td><td>54.0 52.1</td><td>47.6</td><td>40.3</td>

<td>Sizing agent without styrene</td><td>58.1 54.3</td><td>50.1</td><td>44.6</td>

- 10 No. 363355

Also, the values ​​for the water absorption are those available with the invention

Sizing treated papers much better than those treated with the comparison product.