DE19724236A1 - Composition containing reaction product of diisocyanate with two polyalkylene glycols - Google Patents

Abstract

A process for the polarisation of the hydrophobic surfaces of an article is claimed. The surfaces are treated with a polarising agent or the polarising agent is added to an agent used to form the hydrophobic surface. The polarising agent is prepared by reaction of a diisocyanate with a first polyalkylene glycol, derived from a mono alcohol, diol or polyol and having an average mol. wt. of 400-30,000 followed by reaction of the resulting prepolymer with a second polyalkylene glycol, derived from a monoalcohol and having an average mol. wt. of 400-24000. The prepolymer is prepared by addition of 0.8-1.2 moles of diisocyanate per mole of free hydroxyl groups of the first polyalkylene glycol and the polarising agent is formed by addition of 0.8-1.2 moles of the second polyalkylene glycol for each mole of diisocyanate.

Description

The invention relates to a method for polarizing the hy drophobic surfaces of a workpiece, and in particular a Process for polarizing the hydrophobic surfaces of ge glued and / or coated papers.

Workpieces with hydrophobic surfaces are used for numerous Applications needed. The hydrophobic character of the workpiece surface is based either on the selection of a suitable one Workpiece material, such as. B. Teflon, or is in the manufacture the workpiece by adding or applying Water repellents, such as. B. paraffin. One on work with a hydrophobic surface piece is only slightly or no longer wettable with water generally has low water absorbency on. Further processing of workpieces with such hy hydrophobic surfaces using aqueous systems, such as B. printing with water-based inks is ever but only possible if the surface is previously coated with so-called  Wetting agents is treated. These wetting agents reduce everyone the desired hydrophobicity of the workpiece and enable such an unwanted absorption of water. For this reason So far, compromises have had to be accepted with which either largely on processability or the hydrophobicity of the workpiece surfaces has been dispensed with.

There is therefore a need for a method for polarization the hydrophobic surfaces of workpieces, on the one hand the Further workability of the workpieces with aqueous systems possible, but on the other hand the desired hydrophobic properties properties, especially the resistance to ab sorption or water penetration, not deteriorated.

According to the invention, therefore, a method for polarization the hydrophobic surfaces of a workpiece, which is characterized in that the surfaces with egg treated with a polarizing agent or polarisie agent, if necessary, already during the manufacture of the Workpiece, a ver to form the hydrophobic surfaces added agent is added, the polarizing agent is available by reacting a diisocyanate with a Most polyalkylene glycol, the first polyalkylene glycol from a monool, diol or polyol is derived and a medium Molecular weight ranging from about 400 to about 30,000 points, and then reacting the prepoly thus formed mers with a second polyalkylene glycol, the second Po lyalkylene glycol is derived from a monool and a medium res molecular weight in the range of about 400 to about 24,000 has, and wherein to form the prepolymer about 0.8 to 1.2 moles of diisocyanate per mole of free hydroxyl groups from the first Polyalkylene glycol and to form the polarizing agent about 0.8 to 1.2 moles of the second polyalkylene glycol per mole of dii socyanat can be used.  

The diisocyanate and the first and second polyalkylene glycol Kol are preferably in stoichiometric amounts set. Are particularly preferred for the formation of the prepolymer about 1 mole of diisocyanate per mole of free hydroxyl groups Most polyalkylene glycol and to form the polarizing agent about 1 mole of the second polyalkylene glycol per mole of dii socyanat used. The average molecular weight of the first Polyalkylene glycol is preferably in the range between about 4,500 and 9,000, while the average molecular weight of the second polyalkylene glycol preferably between about 2,600 and 4,800 lies.

The workpiece used in the method according to the invention can be made of glass, natural and artificial stone, rubber, paper, Cardboard, ceramics, leather, textiles, metal, plastic and wood existing group can be selected. According to a particularly be preferred embodiment, a glued Pa pier used. The polarizing agent in this case added to the sizing agent (i.e. the water repellent) and, if necessary, in a known manner using a glue press applied. According to a further embodiment of the Invention is a coated paper as the workpiece turns and the polarizing agent is added to the coating color. The coating color is in a known manner in a coating applied.

That to form the prepolymer by reacting with a slide First polyalkylene glycol used in socyanate is preferred an addition product of ethylene oxide and / or propylene oxide a monool, diol or polyol. Use that as a starter molecule The monool, diol or polyol is preferably glycerol, Sorbi tol, sucrose or trimethylolpropane. The polyalkylene glycol can be a block copolymer or a polymer with statistical ver division of the ethylene oxide and propylene oxide units. The The number of alkylene oxide units preferably varies between 8 and 600, particularly preferably between 100 and 150.  

The one used to react with the first polyalkylene glycol Diisocyanate is preferably an aromatic diisocyanate, be toluene diisocyanate is particularly preferred.

The second polyal used to react with the prepolymer kylene glycol is preferably an addition product of ethylene oxide and / or propylene oxide to a monool, being the monool preferably methanol or butanol can be used. The polyalky Lenglycol can be a block copolymer or a polymer with stati tical distribution of the ethylene oxide and propylene oxide units be. The number of alkylene oxide units is preferably in Range from 8 to 400, here preferably between 60 and 80. The second polyalkylene glycol particularly preferably has about 70 Ethylene oxide and / or propylene oxide units.

The polarizing agent can be used alone or in combination with the Mit used to form hydrophobic surfaces agents, for example paraffins, synthetic sizing agents, Polymers or starch. Preferably that is Polarizing agent to form the hydrophobic surface Area used means in an amount of 0.05 to 1.0 Ge percent by weight, particularly preferably in an amount of 0.1 to 0.3 percent by weight, based in each case on the solids content added to the mixture.

The method according to the invention produces workpieces with polar Hydrophobic surfaces that prevent penetration are extremely resistant to water, but at the same time can be processed further using aqueous systems nen. For example, by adding the polarization using a glue to make a fully sized paper be witnessed that absorbs almost no water, the surface compared to conventional fully glued papers is much more wettable. The same effect can be seen  also by adding the polarizing agent to one Get coating color.

The pola achieved with the aid of the method according to the invention Rization of the hydrophobic surfaces can be determined by a measurement of the interfacial energy with the polarizing agent treated or gebil with the addition of the polarizing agent Detected hydrophobic surface. Since it is but the workpieces are solids is a direct one te measurement of the interfacial energy not possible. The determinations The interfacial energy must therefore be measured using indirect methods take place, such as. B. be a contact angle measurement with liquids known surface tension.

The contact angle of a liquid drop applied to a solid is determined by the balance of forces in the three-phase contact solid / liquid / gaseous. From this balance follows the equation introduced by Young:

γ _s = γ _l cosΘ + γ _sl

in the γs the interfacial energy of the solid, γ _l the surface tension of the liquid used for the measurement, γ _sl the interfacial energy at the phase transition solid / liquid and Θ the contact or contact angle.

In the case of a contact angle Θ <90 °, the solid is replaced by the Liquid wetted. A contact angle Θ <90 ° indicates that the Solids not or only partially from the liquid is networked.

In practice there are a number of factors that affect the value of the contact angle Θ can also influence. To do this tough Among other things, the macroscopic roughness of the solid pers, the chemical heterogeneity of the solid surface and  the dissolving power of the wetting liquid as well chemical reactions that start when the liquid acts on the solid surface for a long time.

In many cases, these factors can be eliminated by measuring the so-called static advancing contact angle Θ _a , which can be obtained, for example, using the dynamic contact angle method (DRM). In this method, the solid sample to be examined is arranged on a movable measuring table, a syringe containing the desired liquid is selected with the aid of a control and a drop of liquid is applied to the solid surface via a cannula. With the help of a video camera, an image of the liquid drop is recorded and evaluated in real time using a personal computer. This apparatus enables, among other things, the measurement of the static advancing edge angle Θa, for the determination of which the drop is continuously enlarged so that it constantly wets a fresh solid surface. In this case, the wetting angle is only measured when the movement of the liquid drop is stopped, ie the liquid pressure in the cannula is zero.

To determine the interfacial energy γ _{s of} a solid, it is necessary to measure the contact angle with several liquids known surface tension. To obtain meaningful values, one separates the interfacial energy γs according to the Owens-Wendt-Rabel-Kaelble method into a dispersive (hydrophobic) and a polar part:

γ = γ ^d + γ ^p .

The dispersive component γ ^d interfacial energy is based almost exclusively on London-van der Waals forces. The polar part γ ^{p of} the interfacial energy, on the other hand, is determined, for example, by dipole-dipole, inductive and acid-base forces as well as hydrogen bonds.

From theoretical considerations, taking into account Young's equation above, the following evaluation equation results:

where γ _l and γ _{s have} the meanings given above and the superscript indices d and p denote the dispersive or polar portion of γ _l and γ _s , respectively. By measuring the contact angle Θ _a using several liquids with known values for γl, γl ^d and γl ^p , the unknown sizes of the solid surface γs ^d and γs ^p can be determined from this equation by linear regression.

Further features and advantages of the invention result for preferred embodiment from the following description forms.

Example 1: Preparation of the polarizing agent

To produce a ver Reversible polarizing agent was toluene diisocyanate with egg implemented first polyalkylene glycol at room temperature. The first polyalkylene glycol was an addition product of ethylene oxide on glycerol with an average molecular weight of about 6,000. The ethylene oxide content was approximately 130 units. Per mole Free hydroxyl groups of the polyalkylene glycol became about 1 mole Toluene diisocyanate used. The so obtained Prepolymer was then mixed with a second polyalkylene glycol kol implemented. The second polyalkylene glycol was an addition  product of ethylene oxide on butanol with a medium molecule lar weight of about 3,500. The ethylene oxide content was approximately 80 Units. The second was to react with the prepolymer Polyalkylene glycol preferably used in excess, so that no reactive diisocyanate groups returned after the reaction remained.

The polarizing agent thus obtained is in water under Bil a colorless, clear to greenish-yellow, cloudy solution soluble and has a pH of between 6 and 8.

Example 2: Polarization of the surface of a glued Paper

Using an alkyl ketene dimer with urea and paraffin additives as a sizing agent, a sized paper with a basis weight of 40 g / m ^{2 was} produced. The sizing he followed in a known manner by adding the sizing agent to the mass. The dried, sized paper was then subjected to surface sizing in a further size press. A 6% strength starch liquor with different additives of the polarizing agent obtained according to Example 1 was used here as the sizing agent. The composition of the sizing agents used for surface sizing is given in Table 1 below.

Composition of ver for surface sizing applied sizing agent

Composition of ver for surface sizing applied sizing agent

In Table 1, Sample No. 2-1 denotes one with the alkyl ketendimer sized paper that is made without the use of a lei detergent for surface sizing by the size press ren was. Sample No. 2-2 designates this using the Alkylketendimers glued paper, without further surfaces plot. Sample No. 2-3 designates this using a Alkylketendimers glued paper, the surface of which in one Size press was treated with a 6% starch liquor. The Samples Nos. 2-4 to 2-6 correspond to sample No. 3, with the 6% starch liquor, however, different weight percentages of the polarizing agent, based in each case on the solid matter stop the starch solution, were added.

With the help of the dynamic contact angle method described above, the static advancing contact angle Θ _a and the interfacial energies of the samples thus obtained were determined. Water, glycerin, formamide and ethylene glycol were used as measuring liquids. In addition, the Cobb values were determined in accordance with the international standard ISO 535 (DIN EN 20535), which represent a measure of the water absorption capacity of papers. The Cobb 60 '' value is the calculated water mass that is absorbed by 1 m ² paper or cardboard in 60 seconds under the conditions specified in the standard. The results obtained are shown in Tables 2 and 3 below.

Table 2: Results of contact angle measurements

Table 3: Interface energies and Cobb 60 '' values the glued papers

From Table 2 above it can be seen that the using contact angle measured by water by adding the polarisie means decreases significantly, d. that is, with the addition of the Pola to the one used for surface sizing Starch liquor obtained paper surface is much better networkable. This result correlates with that from Table 3 significant increase in the polar portion of the  Interface energy due to the addition of polarizing agent. At the same time, the Cobb 60 '' values remain almost unchanged different. The addition of the polarizing agent therefore causes one better wettability of the glued paper with water without the resistance of the paper to penetration by Water or water absorption capacity disadvantageously to change.

Example 3: Polarization of coated paper

In the same manner as described in Example 2, paper sized with an alkyl ketene dimer was obtained. The paper had a basis weight of 80 g / m ² . The sized paper was then treated in a coating machine with a coating color which had a pigment content of 100% chalk with a solids content of 59.3% and a pH of 9.0. In further experiments, this coating color was added with different amounts of the polarizing agent obtained according to Example 1. The following table 4 shows the compositions of the coating color, the respective proportions of polarizing agent, in each case based on the solids content of the coating color, and the amount applied to the size paper.

Table 4: Composition of the coating color

Using the dynamic contact angle method described above were the interfacial energies γs of the samples thus obtained Right. The measurements of the static advancing edge angles were made both on uncalendered and on calendered Pro ben made to the influence of surface roughness equalize examined samples for the measurement result. About that In addition, as described in Example 2, the Cobb 60 " Values for the water absorption capacity determined. Get the Results are shown in Tables 5 and 6 below ben.  

Table 5: Results of the contact angle measurements

Table 6: Interface energies and Cobb 60 '' values of coated papers

It can be seen from the results given in Tables 5 and 6 that the addition of the polarizing agent to the coating color significantly increases the polar fraction of the interfacial energy γ _s ^p compared to the conventional coating color. The decrease in the values obtained for the contact angle with water from 101.8 ° for the coating color without addition of polarizing agent to 66.9 ° with a polarizing agent proportion of 1% to 45.70 with a polarizing agent proportion of 5% also indicate that only the polarizing agent addition ensures a wettability of the coated paper with the coating color. Nevertheless, this increased wettability does not lead to an undesirable increase in the water absorption capacity. Because of the increased wettability, the addition of polarizing agent thus results in a significantly better processability with aqueous systems while at the same time maintaining the desired hydrophobic properties of the coated paper.

Example 4: Polarization of coated paper

In the same way as described in Example 3, the ge glued paper from example 2 treated with a coating color. The composition of the coating color, as well as the added Amounts of polarizing agent are in Table 7 below specified. Get the percentages of polarizing agents each on the solids content of the coating color.

Table 7: Composition of the coating color

The interfacial energies γ _{s of} the samples thus obtained were determined using the dynamic contact angle method described above. In addition, as described in Example 2, the Cobb 60 ″ values for the water absorption capacity were determined.

The results obtained are shown in Tables 8 below and 9 indicated.

Table 8: Results of the contact angle measurements

Table 9: Interfacial energies and Cobb 60 '' values of the stri paper

The result given in Tables 8 and 9 correlates with the results obtained above for the use of a 100% chalk coating color. The addition of polarizing agent causes a significant increase in the polar portion of the interfacial energy γs ^P compared to the conventional coating color. At the same time, the contact angle obtained with water decreases. The Cobb 60 '' values remain essentially constant despite the improved wettability.

Comparative example

The experiment from Example 4 was carried out using the method described in this Example described standard coating color repeated, the 1.0 % By weight, based on the solids content of the coating color, one commercial wetting agent (Silastan C2, available from Schill & Seilacher GmbH & Co., Böblingen, Germany) were set. The results obtained for this coating color the contact angle measurements are given in Table 10 below ben.

Table 10: Static advancing edge angles Θa

When measuring the interfacial energies and the Cobb 60 '' values of the coated paper thus obtained were the following Results obtained in Table 11 obtained.

Table 11: Interface energies

The comparison of the commercial wetting agent Silastan C2 with the results obtained for the sample No. 4-3 from the table len 8 and 9 clearly shows that the conventional wetting agent as expected, the wettability of the coated paper increased, but at the same time by the water absorption capacity increased over 25%. This undesirable effect occurs when using not use the polarizing agent according to the invention.

Claims (25)

1. A method for polarizing the hydrophobic surfaces of a workpiece, characterized in that the surfaces are treated with a polarizing agent or the polarizing agent is added to an agent used to form the hydrophobic surfaces, the polarizing agent being obtainable by reacting a diisocyanate with a first polyalkylene glycol , wherein the first polyalkylene glycol is derived from a monool, diol or polyol and has an average molecular weight in the range from about 400 to about 30,000, and then reacting the prepolymer thus formed with a second polyalkylene glycol, wherein the second polyalkylene glycol is derived from a monool and has an average Molecular Weight in the range of about 400 to about 24,000, and about 0.8 to 1.2 moles of di isocyanate per mole of free hydroxyl groups of the first polyalkylene glycol to form the prepolymer and sth. to form the polarizing agent a 0.8 to 1.2 moles of the second polyalkylene glycol are used per mole of diisocyanate. 2. The method according to claim 1, characterized in that the diisocyanate and the first and second polyalkylene Glycol can be used in approximately stoichiometric amounts. 3. The method according to claim 1 or 2, characterized in that to form the prepolymer about 1 mole of diisocyanate each Moles of free hydroxyl groups of the first polyalkylene glycol and to form the polarizing agent about 1 mole of the second Polyalkylene glycol can be used per mole of diisocyanate. 4. The method according to any one of the preceding claims characterized in that the workpiece is made of glass, Natural and artificial stone, rubber, paper, cardboard, ceramics, Leather, textiles, metal, plastic and wood existing Group is selected. 5. The method according to claim 4, characterized in that as the workpiece uses a sized paper and that Polarizing agent is added to a sizing agent. 6. The method according to claim 4, characterized in that used coated paper as the workpiece and that Polarizing agent is added to the coating color. 7. The method according to any one of claims 1 to 6, characterized characterized in that as the first polyalkylene glycol Addition product of ethylene oxide and / or propylene oxide the monool, diol or polyol is used. 8. The method according to claim 7, characterized in that the first polyalkylene glycol is an ethylene oxide and / or Has propylene oxide content of 8 to 600 units. 9. The method according to claim 8, characterized in that the ethylene oxide and / or propylene oxide content in the range is between about 100 and 150 units.   10. The method according to claim 7, characterized in that uses a block copolymer as the first polyalkylene glycol becomes. 11. The method according to claim 7, characterized in that as the first polyalkylene glycol a copolymer with stati static distribution of ethylene oxide and propylene oxide units is used. 12. The method according to any one of claims 1 to 11, characterized ge indicates that the average molecular weight of the first Polyalkylene glycol in the range between about 4,500 and 9,000 lies. 13. The method according to any one of the preceding claims, since characterized in that as the first polyalkylene glycol one of glycerin, sorbitol, sucrose or trimethylol Propane derived polyalkylene glycol is used. 14. The method according to any one of the preceding claims characterized in that the second polyalkylene glycol average molecular weight in the range of about 2,600 to about 4,800. 15. The method according to any one of the preceding claims, since characterized in that as the second polyalkylene glycol an addition product of ethylene oxide and / or propylene oxide to the monool. 16. The method according to claim 15, characterized in that use a block copolymer as the second polyalkylene glycol det. 17. The method according to claim 15, characterized in that as the second polyalkylene glycol, a copolymer with statistical distribution of the ethylene oxide and propylene oxide units is used.   18. The method according to claim 15, characterized in that the ethylene oxide and / or propylene oxide content in the range is between about 60 and 80 units. 19. The method according to claim 18, characterized in that the ethylene oxide and / or propylene oxide content about 70 units ten. 20. The method according to any one of the preceding claims characterized in that as the second polyalkylene glycol a polyalkylene glycol derived from methanol or butanol is used. 21. The method according to any one of the preceding claims characterized in that as the diisocyanate an aromatic cal diisocyanate is used. 22. The method according to any one of the preceding claims, characterized in that as the diisocyanate Toluoldi Isocyanate is used. 23. The method according to any one of the preceding claims, characterized in that the polarizing means for Formation of the hydrophobic surface used in agents an amount of 0.05 to 5.0 wt .-%, based on the Solids content is added. 24. The method according to claim 23, characterized in that a sizing agent to form the hydrophobic surface used and the polarizing agent in an amount of 0.1 to 0.3 wt .-% is added. 25. The method according to claim 23, characterized in that a coating color to form the hydrophobic surface used and the polarizing agent in an amount of 1 up to 5 wt .-% is added.