DE102008000126A1 - Preparing polyurea elastomer containing roll coating agent, useful e.g. to treat paper, comprises reacting diamine- and diisocyanate-compound to give prepolymer, mixing prepolymer with two different diamine compounds and applying on roll - Google Patents

Abstract

Preparation of at least a polyurea elastomer containing roll coating agent, comprises (a) preparing a prepolymer by reacting at least an alpha ,omega -diamine compound with at least an aliphatic or cycloaliphatic diisocyanate compound; (b) mixing the prepolymer with at least two different alpha ,omega -diamine compounds and (c) applying the obtained mixture on a rotating roll, where the compounds used in the step (b) are selected in such a way that the pot time of the step (b) is 5-60 seconds. An independent claim is included for roll coating agent obtained by the above process.

Description

The The present invention relates to a method for producing at least one a polyurea elastomer-containing roll cover by means of rotational molding.

Around the surfaces of rolls required in their use application properties, in particular a sufficient Abrasion resistance, tear resistance, impact resistance, hardness and the like, rolls on their surface usually become with a roll cover or a roll coating or a roll cover Mistake. For this purpose, for example, plastic coverings, such as polyurethane coatings used. From Polyurethane roll lining materials known from the prior art However, for many applications, such as for rolls used in the paper industry, insufficient Properties, in particular an improvement in need of improvement Abrasion resistance and impact resistance, on and therefore often felt as unsatisfactory.

It Coatings of polyurea elastomers have also been proposed which has good abrasion resistance and temperature resistance exhibit. However, such coatings are used in the State of the art known methods by spraying applied to the substrate to be coated, not least in the high reactivity of the diisocyanate compounds used and diamine compounds is founded. In a spraying process becomes a starting material for polyurea, namely a diamine compound and a diisocyanate compound or an isocyanate group containing prepolymer containing aerosol in several thin layers applied to the substrate to be coated. Upon impact of the aerosol on the substrate naturally get in the aerosol contained, harmful compounds in the ambient atmosphere. Furthermore, they have with them Process produced polyurea coatings an insufficient Liner bond strength on. In addition, those with this procedure available yields in need of improvement.

task It is therefore the object of the present invention to provide a process for the preparation a roll cover to provide a roll covering with a high abrasion resistance, with a high temperature resistance, with a good hydrolysis resistance and in particular with a good liner bond strength, which results in a has high yield, which is carried out inexpensively which is also environmentally friendly.

• a) Herstellen eines Präpolymers durch Reagieren wenigstens einer α,ω-Diaminverbindung mit wenigstens einer aliphatischen oder cycloaliphatischen Diisocyanatverbindung,
• b) Vermischen des in Schritt a) hergestellten Präpolymers mit wenigstens zwei verschiedenen α,ω-Diaminverbindungen und
• c) Aufbringen der in Schritt b) hergestellten Mischung auf eine rotierende Walze, wobei

die in dem Schritt b) eingesetzten Verbindungen so ausgewählt werden, dass die Topfzeit der in dem Schritt b) hergestellten Mischung 5 bis 60 Sekunden beträgt.According to the invention, this object is achieved by providing a process for producing a roll covering containing at least one polyurea elastomer by means of rotational casting, which comprises the following steps:

• a) preparing a prepolymer by reacting at least one α, ω-diamine compound with at least one aliphatic or cycloaliphatic diisocyanate compound,
• b) mixing the prepolymer prepared in step a) with at least two different α, ω-diamine compounds and
• c) applying the mixture prepared in step b) to a rotating roller, wherein

the compounds used in step b) are selected such that the pot life of the mixture produced in step b) is 5 to 60 seconds.

By doing the mixture of prepolymer obtained in process step b) and at least two different α, ω-diamines applied by rotation to the rotating roll to be coated becomes, becomes a pollution of the ambient atmosphere with harmful chemical compounds, such as Diamine compounds and diisocyanate compounds prevented. In addition, will by the pot life of the process step b) Mixing between 5 and 60 seconds ensured that the polyurea elastomer in the process step c) evenly and in the desired Thickness can be applied to the rotating roller. By in the process step b) two different α, ω-diamine compounds can be used, the pot life of the mixture to a desired Value to be set. Furthermore, with this method, a roll covering obtained with excellent interlayer bond strength, since the roll cover are applied in a layer on the roller can. In addition, the inventive method a good yield of polyurea elastomer and is inexpensive feasible. Finally, they are the ones with obtainable by the process according to the invention Polyurea elastomer roll coverings by a high Abrasion resistance, through a good temperature resistance and by a high hydrolysis resistance. From the The above reasons are suitable with these roll coverings provided rolls especially for use in the paper industry, namely, for example, for treatment a paper, board, tissue or other fibrous web in a machine for the production and / or refinement thereof.

For the purposes of the present invention, rotational molding is understood to mean a process in which a liquid mixture, that is to say no aerosol, is sprayed onto the surface of a rotating substrate, ie onto the surface of a rotating substrate Outer peripheral surface of a roller is applied.

Further denotes the term pot life in the sense of the present invention the processability time of a reactive mixture at the processing temperature, specifically the time span between the mixing of the components in the step b) and the time at which the mixture has reached a viscosity of 100,000 mPa · s. For example, the pot life can be determined by that in the Process step a) prepared prepolymer and the two α, ω-diamines in the process step b) each having a temperature of 80 ° C. simultaneously in a befindliches on a heatable magnetic stirrer and heated to 80 ° C beaker, for example a 200 ml beaker, filled and by the magnetic stirrer be mixed together and from the time of mixing measured at the time until the mixture has a viscosity of 100,000 mPa · s has reached.

In order to allow sufficient for the application by rotational molding pot life of the mixture to be produced in step b) between 5 and 60 seconds, in process step a) of the inventive method, an aliphatic or cycloaliphatic diisocyanate compound is used, since aromatic and partially aromatic diisocyanate such a high reactivity show that they would lead to too short a pot life. The at least one diisocyanate compound used in process step a) preferably has the following general formula (I): OCN-R ¹ -NCO (I), wherein R ^{1 is} an aliphatic C ₄ -C ₁₂ group or a cycloaliphatic C ₆ -C ₁₈ group.

Especially good results are both in terms of mechanical properties of the produced polyurea elastomer as well as with respect to the pot life of the mixture produced in process step b) obtained when the at least one used in the process step a) Diisocyanate compound is selected from the group which from dicyclohexylmethane-4,4'-diisocyanate (HMDI), isophorone diisocyanate (IPDI), hexamethylene-1,6-diisocyanate (HDI), 2,4,4-trimethylhexamethylene-1,6-diisocyanate (TMDI), 1,4-cyclohexyl diisocyanate (CHDI), 1,3-bis (isocyanatomethyl) cyclohexane (HXDI), 1,3-xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI) and any combination of two or more of the aforementioned compounds consists.

According to a further preferred embodiment of the present invention, the at least one diamine compound used in process step a) has the following general formula (II): R ² HN-R ³ -NHR ⁴ (II), wherein
R ² and R ⁴ , independently of one another, are hydrogen, a C ₄ -C ₁₂ aliphatic group or a C ₆ -C ₁₈ cycloaliphatic group and
R ^{3 is} an aliphatic C ₄ -C ₁₂ group, a cycloaliphatic C ₆ -C ₂₀ group, a C ₆ -C ₂₀ aromatic group, a partially aromatic C ₆ -C ₁₄ group, a saturated aliphatic, cycloaliphatic or partially aromatic polyester , is a saturated aliphatic, cycloaliphatic or partially aromatic polyether or a saturated aliphatic, cycloaliphatic or partially aromatic polycarbonate. If, in this embodiment, the radical R ^{3 of} the diamine compound used is an aliphatic, cycloaliphatic or partially aromatic polyester, a saturated aliphatic, cycloaliphatic or partially aromatic polyether or a saturated aliphatic, cycloaliphatic or partially aromatic polycarbonate, this radical preferably has a weight-average molecular weight of between 200 and 5,000 g / mol, more preferably a weight average molecular weight between 700 and 3000 g / mol and most preferably a weight average molecular weight between 900 and 2100 g / mol. Also, in the case where a diamine compound having no polyester, polyether or polycarbonate group as R ³ is used in the process step a), the weight average molecular weight of the diamine compound used is preferably 200 to 5,000 g / mol.

Either in view of the mechanical properties of the invention with the Process prepared polyurea elastomer as well as in terms on the pot life of the produced in the process step b) Mixture in the process step a) the diisocyanate compound and the diamine compound is preferably used in such amounts, that the molar ratio between the diisocyanate compound and the diamine compound is 4: 1 to 2: 1.

Preferably the method step a) is carried out such that the resulting prepolymer has a viscosity between 100 and 5,000 mPa · s, preferably between 200 and 1,000 mPa · s and more preferably between 300 and 700 mPa · s. Usually the reaction temperature is in the process step a) between 25 and 140 ° C and preferably between 50 and 100 ° C.

In order to achieve a suitable crosslinking density after mixing in process step b), the α, ω-diamine compound is proposed in a further development of the inventive concept and to use the diisocyanate compound in process step a) in such amounts and to carry out the reaction in this process step such that the prepolymer obtained has an isocyanate content between 5 and 20%, preferably between 8 and 16% and particularly preferably between 10 and 14%.

As already stated, it is for the invention Process essential that the pot life of the in the process step b) is between 5 to 60 seconds, so that the mixture in the process step c) by means of rotational molding evenly applied to the rotating roller can be. In this case, the pot life of the mixture in particular also by the reactivity of those used in process step b) Diamine compounds determined. Basically you can in process step b) all α, ω-diamine compounds are used, which after mixing with the in the process step a) produced prepolymer has a pot life between 5 and 60 seconds. This can be achieved in particular if in process step b) at least one of the two different α, ω-diamine compounds has the general formula (II). Especially good results will be achieved in this regard, if all in the process step b) various α, ω-diamine compounds used have the general formula (II).

Around to obtain a suitable pot life of the mixture is in further development proposed in the inventive concept, in the process step b) at least one first comparatively reactive diamine compound and at least one second comparatively unreactive diamine compound use, wherein the at least one first comparatively reactive Diamine compound, preferably from bis (4-aminocyclohexyl) methane, 1,4-diaminobutane, 1,4-diaminocyclohexane, 1,5-diaminopentane, 1,6-diaminohexane, α, ω-polypropyleneglycol diamine and any combinations of two or more of the foregoing Compounds existing group is selected and the at least one second comparatively unreactive diamine compound preferably from diethyltoluenediamine, methyldiethanolamine (MDEA), Methylenebis (3-chloro-2,6-diethylaniline) (MCDEA), 4,4'-diamino-3,3'-dichlorodiphenylmethane (MOCA) and any combination of two or more of the foregoing Connections existing group is selected.

According to one further preferred, to the aforementioned embodiment alternative embodiment of the present invention be in the process step b) at least two different diamine compounds each used with moderate reactivity. At this Embodiment will be the at least two different Diamine compounds preferably, each independently that of m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, methylenedianiline and any combinations of two or more of the foregoing Connections existing group selected.

Quality In particular, results are obtained when in the process step b) used diamine compounds each have an amino group content from 0.4 to 50 mmol / g.

Preferably become the prepolymer and the at least two different Diamine compounds in process step b) in such amounts mixed together that the molar ratio between the isocyanate groups and the amine groups 0.8: 1 to 1.2: 1.

A good processability of the produced in the process step b) Mixture by means of rotational molding is achieved in particular when the compounds used in process step b) are selected be that the pot life of the mixture prepared in step b) 5 to 15 seconds and preferably 8 to 12 seconds.

Around a uniform application and curing the mixture of process step b) on or on the rotating (s) Achieve roller, is in development of the inventive concept proposed, the roller in the process step c) with a peripheral speed from 15 to 80 meters / minute, and more preferably from 20 to 50 meters / minute to rotate. The liquid ejection in the rotational molding on the roller, for example, 500 to 15,000 g / min. be, with an output between 2,000 and 12,000 g / min. and particularly an output between 3,000 and 10,000 g / min. especially is preferred.

One Another object of the present invention is a with the above described inventive method available Roller cover.

Of the obtainable by the process according to the invention Polyurea elastomer roll coating has high abrasion resistance, a good hydrolysis resistance and a high temperature resistance on. In addition, the invention is characterized Roll coating by an excellent intermediate layer bond strength out.

Preferably, the according to the DIN 53616 measured abrasion of the roll cover according to the invention 5 to 50 mm ³ and / or is the tension of the roll covering at 10% elongation in the tensile test according to the DIN 53504 After 28 days storage at 95 ° C water storage 95 to 70% of the initial value.

in principle The thickness of the roll cover can vary depending on the later application of the roller can be freely selected. Usually the thickness of the roll cover is 10 to 25 mm.

According to one another preferred embodiment of the present invention the roll coating has a softening point between 140 and 250 ° C.

Preferably the glass transition temperature of the roller covering is -50 up to 80 ° C.

One Another object of the present invention is a roller for Treatment of a paper, board, tissue or other fibrous web in a machine for the production and / or refinement thereof, which on their surface, d. H. on its outer peripheral surface, with the invention described above Roll coating is coated.

following the invention will be described with reference to an embodiment of the present invention, but not restrictive example explained in more detail.

example 1

In a first step a prepolymer was prepared by reaction between HMDI and an α, ω-Polypropylenglykoldiamin (Jeffamine ^® DA 2000) at a processing temperature of 80 ° C. After the reaction, the reaction mixture was degassed.

Then, a mixture of three diamine compounds was prepared having the following composition:
50 wt .-% α, ω-Polypropylenglykoldiamin (Jeffamine ^® DA 2000),
35 wt .-% diethyltoluenediamine and
15% by weight of bis (4-aminocyclohexyl) methane.

These Mixture was then heated to 80 ° C.

about Two separate hoses were a mixing head of the rotor / stator principle continuously with the produced in the first step prepolymer a temperature of 80 ° C and the aforementioned, the three Diaminverbindungen containing mixture having a temperature of also 80 ° C in a molar ratio of Fed 1: 1 and the two components in the mixing head mixed together. The liquid jet produced during the mixing was continuous with a total output of 3,500 g / min. to one with a peripheral speed of 25 meters / minute rotating roller applied. The feed of the roller was at the mixing head 7 mm / U.

It a roll coating with a thickness of 15 mm was obtained, which has excellent abrasion resistance, hydrolysis resistance, Temperature resistance and interlayer bond strength had. The interlayer bond strength of the obtained roll cover was significantly better than one by means of a spraying process obtained comparative roller.

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited non-patent literature

• - DIN 53616 [0024]
• - DIN 53504 [0024]

Claims (24)

Process for the preparation of at least one Polyurea elastomer containing roll cover by means of rotational molding comprising the steps: a) Preparation of a prepolymer by reacting at least one α, ω-diamine compound with at least one aliphatic or cycloaliphatic diisocyanate compound, b) Mixing the prepolymer prepared in step a) with at least two different α, ω-diamine compounds and c) applying the mixture prepared in step b) a rotating roller, wherein those used in step b) Compounds are selected so that the pot life of in the step b) mixture is 5 to 60 seconds. Process according to Claim 1, characterized in that the at least one diisocyanate compound used in step a) has the general formula (I): OCN-R ¹ -NCO (I), wherein R ^{1 is} an aliphatic C ₄ -C ₁₂ group or a cycloaliphatic C ₆ -C ₁₈ group. Method according to claim 2, characterized in that in that the at least one diisocyanate compound used in step a) is selected from the group consisting of dicyclohexylmethane-4,4'-diisocyanate (HMDI), isophorone diisocyanate (IPDI), hexamethylene-1,6-diisocyanate (HDI), 2,4,4-trimethylhexamethylene-1,6-diisocyanate (TMDI), 1,4-cyclohexyl diisocyanate (CHDI), 1,3-bis (isocyanatomethyl) cyclohexane (HXDI), 1,3-xylylene diisocyanate (XDI), tetramethylxylylene diisocyanate (TMXDI) and any combinations consists of two or more of the aforementioned compounds. Process according to at least one of the preceding claims, characterized in that the at least one diamine compound used in step a) has the general formula (II): R ² HN-R ³ -NHR ⁴ (II), in which R ² and R ⁴ , independently of one another, are hydrogen, an aliphatic C ₄ -C ₁₂ -group or a cycloaliphatic C ₆ -C ₁₈ -group and R ^{3 is} a C ₄ -C ₁₂ aliphatic group, a cycloaliphatic C ₆ - C ₂₀ group, a C ₆ -C ₂₀ aromatic group, a partially aromatic C ₆ -C ₁₄ group, a saturated aliphatic, cycloaliphatic or partially aromatic polyester, a saturated aliphatic, cycloaliphatic or partially aromatic polyether or a saturated aliphatic, cycloaliphatic or partially aromatic Polycarbonate is. Process according to Claim 4, characterized in that the radical R ³ in the formula (II) is a saturated aliphatic, cycloaliphatic or partially aromatic polyester having a weight-average molecular weight of 200 to 5,000 g / mol, preferably 700 to 3,000 g / mol, particularly preferably 900 to 2,100 g / mol, a saturated aliphatic, cycloaliphatic or partially aromatic polyether having a weight-average molecular weight of 200 to 5,000 g / mol, preferably 700 to 3,000 g / mol, particularly preferably 900 to 2100 g / mol, or a saturated aliphatic, cycloaliphatic or partially aromatic polycarbonate having a weight-average molecular weight of 200 to 5,000 g / mol, preferably 700 to 3,000 g / mol, particularly preferably 900 to 2,100 g / mol. Method according to at least one of the preceding claims, characterized in that the at least one used in step a) Diamine compound has a weight average molecular weight of 200 to 5,000 g / mol. Method according to at least one of the preceding claims, characterized in that the diisocyanate compound and the diamine compound in step a) are used in such amounts that the molar ratio between the diisocyanate compound and the diamine compound is 4: 1 to 2: 1. Method according to at least one of the preceding claims, characterized in that the one produced in step a) Prepolymer has a viscosity between 100 and 5,000 mPa · s, preferably between 200 and 1000 mPa · s and more preferably between 300 and 700 mPa · s. Method according to at least one of the preceding claims, characterized in that the one produced in step a) Prepolymer an isocyanate content between 5 and 20%, preferably between 8 and 16%, and more preferably between 10 and 14%. Method according to at least one of the preceding Claims, characterized in that at least one, preferably two, the diamine compounds used in step b) have the general formula (II). Method according to at least one of the preceding claims, characterized in that in step b) at least one first diamine compound is used, which consists of the bis (4-aminocyclohexyl) methane, 1,4-diaminobutane, 1,4-diaminocyclohexane, 1 , 5-diaminopentane, 1,6-diaminohe xan, α, ω-polypropylene glycol diamine and any combination of two or more of the aforementioned compounds is selected, and at least one second diamine compound is used, which consists of the diethyltoluenediamine, methyldiethanolamine (MDEA), methylenebis (3-chloro-2, 6-diethylaniline) (MCDEA), 4,4'-diamino-3,3'-dichlorodiphenylmethane (MOCA) and any combination of two or more of the aforementioned compounds. Method according to at least one of the claims 1 to 10, characterized in that in the step b) at least two diamine compounds are used, each of which Selected from the group consisting of m-phenylenediamine, o-phenylenediamine, p-phenylenediamine, methylenedianiline and any combinations consists of two or more of the aforementioned compounds. Method according to at least one of the preceding Claims, characterized in that in the step b) used diamine compounds an amino group content of 0.4 to 50 mmol / g. Method according to at least one of the preceding Claims, characterized in that the prepolymer and the at least two diamine compounds in step b) in be used such amounts that the molar ratio between isocyanate groups and amine groups 0.8: 1 to 1.2: 1. Method according to at least one of the preceding Claims, characterized in that in step b) compounds selected so that the pot life of the mixture 5 bis produced in step b) 15 seconds and preferably 8 to 12 seconds. Method according to at least one of the preceding Claims, characterized in that in the step b) mixture applied in step c) on a roller which is at a peripheral speed of 15 to 80 meters / minute, preferably from 20 to 50 meters / minute, rotated. Method according to at least one of the preceding Claims, characterized in that in the step b) produced in the step c) with an output of 500 to 15,000 g / min, preferably 2,000 to 12,000 g / min and especially preferably 3,000 to 10,000 g / min. is applied to the roller. Roll coating obtainable by a method according to one of claims 1 to 17. Roll covering according to claim 18, characterized that this has a thickness between 10 and 25 mm. Roll lining according to claim 18 or 19, characterized in that the measured according to DIN 53616 abrasion of the roll lining is 5 to 50 mm ³ . Roll covering according to at least one of the claims 18 to 20, characterized in that the tension of the roll cover at 10% elongation in the tensile test according to DIN 53504 After 28 days storage at 95 ° C water storage 95 to 70% of the initial value is. Roll covering according to at least one of the claims 18 to 21, characterized in that the softening point of Roll coating is 140 to 250 ° C. Roll covering according to at least one of the claims 18 to 22, characterized in that the glass transition temperature of the roll covering is -50 to 80 ° C. Roller for treating a paper, board, tissue or another fibrous web in a machine for manufacturing and / or finishing the same, characterized in that on the Surface of the roll is a roll covering according to one of the claims 18 to 23 is provided.