DE19528540A1 - Resin mixt. used as low formaldehyde emission binder for fibrous sheets - comprising urea formaldehyde resin, melamine, di:cyano:di:amide and alcohol or ether - Google Patents

Abstract

A novel resin mixt comprises (by wt): (a) 55-98.8% urea-HCHO(UF) resin; (b) 0.1-20% melamine; (c) 0.1-20% dicyandiamide; and (d) 1-30% aliphatic 2-4C alkanol with at least 2 alcoholic OH gps (polyol A) or an ether contg at least 2 alcoholic OH gps and built up from 2-10 units derived form polyol A.

Description

The present invention relates to resin mixtures containing

• (a) 55 to 95% by weight of a urea-formaldehyde resin,
• (b) 1 to 20% by weight of melamine,
• (c) 1 to 20% by weight of dicyandiamide and
• (d) 1 to 30 wt .-% of an aliphatic C₂ to C₄ alkanol with at least two alcoholic hydroxyl groups (polyol A) or one bearing at least two alcoholic hydroxyl groups Ethers made up of 2 to 10 derived from polyol A. Units.

Furthermore, the invention relates to bonded fabrics on Ba sis of fibers produced using the resin blends were made and the use of the bound fabrics based on fibers, especially as inliners for manufacturing of floor coverings and bituminized roofing membranes.

It is well known to use bitumen or plastics in the form of Use webs or foils as coating agents, whereby this by embedding a bound fabric on the basis of fibers, for example a bonded nonwoven such as a glass fiber or plastic impregnated with a binder read, are reinforced. Such sheets or foils are described in Ab dependence on the matrix, d. H. the plastic or bitumen, in which the bonded nonwoven is embedded, for example used as roofing felt or as flooring. It has been shows that the properties, especially what the mechanical Properties of such composite structures, crucial from depend on the mechanical properties of the bonded nonwovens gene.

Bonded nonwovens are also used as filter materials Use that is used for the filtration of aqueous suspensions be set. A high me mechanical strength desired. So that the filter materials at Use in an aqueous environment and have a long service life Contamination of the filtrate is to be avoided as far as possible the binder, even if it has been in contact with water for a long time  clock comes, not be broken down chemically or even dissolve sen.

A high strength of the bonded nonwovens, especially un indirectly after their manufacture, is also necessary because in their manufacture and processing they form a composite the z. B. when winding, impregnating with the serving as a matrix Material and drying are subjected to tensile and shear forces. For this it is necessary that the binder be as short as possible Time after application to the unbound fabrics Basis of fibers hardens and the fabric the required gives strength.

Furthermore, the binders should be produced as economically as possible bar and can be processed into bonded nonwovens. This is necessary changes, for example, that the binders can be stored without they change their properties and that they have no special Precautions regarding occupational hygiene and work have security processed. It is particularly important here that when impregnating the nonwovens and subsequent Drying as few substances that are not released or released into the atmosphere to a limited extent like organic solvents or formaldehyde. Out for this reason, the binders should be in the form of aqueous solvents have solutions processed.

These aqueous solutions should be as unlimited as possible with what Let it dilute and in the process in a solution or dispersion pass that is largely free of sticky coagulate. This Property facilitates the cleaning of objects with which the aqueous solutions during their transportation or processing come into contact, significantly.

DE-A-33 46 679 describes aqueous urea-formaldehyde resins, into which an alkali sulfite is also condensed and their Methylol groups are etherified with alkanols as binders for Nonwovens recommended. However, these binders still contain relatively large amounts of free formaldehyde, of which Ver processing of the resins to form large areas to be released.

From US-A-3 864 296 are aqueous binder solutions and their Use for the impregnation of cellulose fabrics, e.g. B. Pa pier, known. These binder solutions contain, for example the reaction product of a polyvalent carboxylic acid, the contains a C = C double bond and a polyvalent alkylamine, which is then treated with a cationic urea-formaldehyde  Resin is implemented further. To lower the viscosity who which these binders, if necessary, with a multivalent Alcohol, e.g. B. added diethylene or triethylene glycol.

The object of the present invention was therefore a binder for the production of bound flat structures based on ready, who have the desired property profile put. In particular, it should be an aqueous solution process while avoiding high formaldehyde emissions sen.

Accordingly, the resin mixtures defined at the outset and the bonded fibers made from them Fabric found.

The resin mixtures according to the invention contain

• a) 55 to 98.8, preferably 65 to 97.3, particularly preferably 75 to 95.7% by weight of a urea-formaldehyde resin,
• b) 0.1 to 20, preferably 0.2 to 15, particularly preferably 0.3 to 7% by weight melamine,
• c) 0.1 to 20, preferably 0.5 to 15, particularly preferably 1 to 8% by weight of dicyandiamide and
• d) 1 to 30, preferably 2 to 20, particularly preferably 3 to 15 wt .-% of an aliphatic C₂ to C₄ alkanol with mind at least two alcoholic hydroxyl groups (polyol A) or one bearing at least two alcoholic hydroxyl groups Ethers made up of 2 to 10 derived from polyol A. Units.

The urea-formaldehyde resins and their production are all Commonly known and for example in Ullmanns Encyklopadie der technical chemistry, 4th edition, Verlag Chemie GmbH, Weinheim / Bergstrasse, 1973, Volume 7, pp. 403 to 422.

Suitable urea-formaldehyde resins are obtained, for example, by one

• a1) per mole of urea
• a2) 0.5 to 2.5 mol, particularly preferably 1.2 to 1.9 mol, of form aldehyde.

Component (a1) (urea) is preferably in the form of a con centered aqueous solution with formaldehyde coming from the DE-A 24 51 990 and EP-A 0 083 427 is known. These solutions from 2.0 to 6.0, preferably 3.5 to 4.5 mol form aldehyde per mole of urea preferably has a solids content from 50 to 85, preferably from 60 to 80% by weight. They contain Urea and formaldehyde partly in monomeric form, partly in form of reaction products such as methylolureas or lower molecular condensation products.

The formaldehyde (component a2) is preferred, as before wrote in the form of the concentrated aqueous solution with urine substance, as a 30 to 50 wt .-% aqueous solution or as a paraform aldehyde used.

Component (a) is generally prepared in this way before that first the components (a1) and (a2) in an aq solution at 60 to 100, preferably from 75 to 95 ° C and a pH Value of 4.5 to 7.5 can react. To end the reaction the solution is allowed to cool until it reaches a temperature of 10 to 80, preferably from 10 to 30 ° C.

The implementation is generally at pH values in the upper third of the specified pH range, started and gradually in the course of the reaction to a pH value in the lower third of the specified range.

In general, the reaction is carried out until the resulting urea-formaldehyde resin (component a), bezo to a solids content of 60 wt .-%, a viscosity of 30 to 100, preferably 40 to 70.

Component (a) is usually used as an aqueous solution a solids content of 30 to 70, preferably 55 to 60% by weight used. Solutions of component (a) with such a solid are particularly easy to manufacture if they are already held corresponding in the implementation of components (a1) and (a2) Amounts of water are used. However, it is also possible to subsequently adjust the solids content of the solutions len by adding water afterwards or preferably by Distillation at reduced pressure and a temperature of 15 up to 30 ° C water removed.

Mixtures according to the invention with a particularly high intrinsic You get the level of quality especially when you implement it carried out in 4 steps.  

In step 1, components (a2) and (a1) are first Molar ratio 4: 1 to 5: 1 with a pH of 6.5 to 7.5 with implemented each other until an implementation product is created, that, based on a solids content of 45 to 55%, an im Fordbecher determined run-off time of 45 to 65 seconds. It it is believed that in this step it is primarily methylolated Urea is formed.

In step 2, the reaction product obtained in step 1 at a pH of 4.5 to 5.5 further implemented until the im Ford cup determined run-off time, based on a solid content of 45 to 55%, 5 to 65 seconds. Probably in this step the methylolated urea forms higher molecular oligomers that abge from 2 to 5 on average from the urea directed units included.

In step 3, the reaction product obtained in step 2 usually at a pH of 7.0 to 7.5 with this much shape aldehyde added that the ratio component (a2) :( a1) 3.0: 1 to 5.0: 1, preferably 3.0: 1 to 3.5: 1.

In step 4, the reaction product obtained in step 3 with such amounts of urea that the molar ratio (a2) :( a1) is 2.5: 1 to 0.5: 1, preferably 1.9: 1 to 1.2: 1. Be the pH is preferred to one before adding the urea Value decreased from 5.0 to 6.0 and during the addition of urine continuously or in several steps Value set from 7.5 to 8.5.

The residence time in step 1 is usually 15 to 25 minutes at a temperature of 75 to 95 ° C. Step 2 is generally 5 ° C higher than step 1 leads. With dwell times of 20 to 50 minutes, tempera is mostly tures from 80 to 100 ° C required. After adding form aldehyde in step 3, the reaction is usually still for 20 continued to 40 min at a temperature of 80 to 95 ° C. In Step 4 is the reaction mixture before adding the urine material lowered to 40 to 60 ° C, after which this especially before Manufacturing processes by cooling to temperatures of 10 up to 30 ° C is completed.

The commonly used bases can be used to adjust the pH values such as alkali or alkaline earth metal hydroxides, preferably in the form of their aq Rigen solutions and tertiary amines, for. B. Tri- (C₁ to C₆-alkyl) amines and acids such as mineral acids, e.g. B. hydrochloric acid,  Sulfuric acid and phosphoric acid or organic acids, e.g. B. Carboxylic acids such as formic acid can be used.

The components (b) and (c) melamine and dicyandiamide are preferably used in solid form.

Glycerol or a compound are preferred as component (d) of the general formula I

in the
R¹ is hydrogen or methyl and
n is 1 to 10, preferably 1 to 4.

If R¹ occurs several times in the compound of formula (I), residues R¹ with different meanings also side by side lie.

Among the compounds of general formula I are mainly Ethylene glycol, propylene glycol, diethylene glycol, triethylene glycol and tetraethylene glycol is preferred.

The resin mixtures according to the invention are generally characterized by Mixing of components (a) to (d) produced. The Vermi is not critical and is done, for example, by the Components (b), (c) and (d) in the urea-formaldehyde resin stir in.

The mixing of components (a) to (d) can lead to one at that time, for example immediately before Processing of the mixtures according to the invention. Preferably takes mixing immediately after urine production substance-formaldehyde resin before, for example, while you Urea-formaldehyde resin of the usual in the production Cools temperatures to lower temperatures, e.g. B. at 40 up to 60 ° C.

The resin mixtures according to the invention obtained in this way are already tradable in this form and over a period of time Can be stored from approx. 1 to 2 months at approx. 20 ° C without their own  changes significantly. To increase the stock stability and to reduce transportation costs this can aqueous resin mixtures with advantage also in the powder form leads. The generally known ones are particularly suitable for this spray drying process.

The resin mixtures of the invention are more convenient in shape an aqueous impregnation liquor with a content of 15 to 60, preferably from 15 to 30% by weight of the resin according to the invention mix processed.

For this purpose, fabrics based on fibers with these Im impregnating liquors and then partially water or completely removed, which is in the impregnation liquor contained mixture solidified and bound Flat structures based on fibers are created.

To accelerate the solidification of the fabrics, sets acidic catalysts are expediently added to the impregnating liquors, e.g. B. metal salts of strong acids such as magnesium chloride or acids, preferably mineral acids, e.g. B. phosphoric acid. Furthermore can it is advantageous to use the usual impregnation liquors such as wetting agents, colorants, thickeners, plasticizers, water repellents medium, brighteners, preservatives, defoamers, emulsifiers or add adhesion promoters.

Suitable fabrics based on fibers can be made from fibers be of different types. Made of fibers Flat structures are, for example, mats or nonwovens made of mate materials such as cellulose, glass fibers, polyester fibers, ceramic fibers as well as paper and more generally textiles.

The basis weights of the fabrics based on fibers lie gene generally at 20 to 500 g / m².

The impregnation is generally carried out by spraying or Scraper the impregnation liquor or by dipping the surfaces structures based on fibers in the impregnation liquor. Given if an excess of impregnation liquor can then be removed squeezed or sucked.

The order quantities of the impregnation liquor are usually like this chosen that the solids content of the fabrics on Ba sis of fibers after impregnation and removal of what sers increased by 10 to 30%, preferably by 15 to 25%.  

Impregnation in a horizontal is particularly preferred foulard made.

The impregnated materials are used to remove the water 3 at elevated temperature, preferably at temperatures of 100 to 400, in particular from 130 to 280 ° C over a period of preferably dried for 2 to 10 minutes. At these temperatures arises from the components of the mixtures according to the invention high molecular network through which the fibers are firmly connected get connected.

These bonded fabrics based on fibers thus point probably a much higher one, both wet and dry Tear and tensile strength. The flexibility of the Largely preserved materials, d. H. the bound areas structures based on fibers can be bent or rolled.

The bonded fabrics based on fibers can be manufacture particularly easily and economically because at the Processing the impregnation liquors hardly released any formaldehyde and therefore special measures for air pollution control, e.g. B. Treatment of the used to dry the impregnated hot air, spare. Furthermore, parts that are compatible with the Im soaking liquors come into contact, clean easily with water, because they can be diluted with water without sticking coagulate is formed. Furthermore, the imprint stand out kidney liquors with a particularly high reactivity. The before part that is associated with it is that the resin mixes based on their application to the fabric of fibers and drying quickly, so that the herge already made bound fabrics made of fibers shortly after their manufacture, a high tear resistance point, which simplifies their further processing.

The bound flat structures are usually based on Process fibers into composite materials such as sheets or foils by stacking them in one or more layers embedded as a liner in a matrix made of plastic or bitumen.

Compounds of this type can, for example, be coated processing materials, e.g. B. use as flooring or roofing felt Find.

Furthermore, the bound flat structures based on also as filter material or as separators in batteries be used.

Manufacturing examples Resin mixture 1

A mixture of 750 g Formol 50 (aqueous solution of water, Urea and formaldehyde (equivalent to 188 g urea and 375 g Formaldehyde)) and 240 g of a 68% by weight aqueous urea solution was at about 85 ° C and a pH of about 7.0 for 20 min set. The pH was then reduced to approximately 5.0 and the reaction continued at a temperature of about 90 ° C until the reaction mixture has an expiry time determined in the Ford cup of 55 s. Thereafter, the last named temperature 379 g of a 40 wt .-% aqueous form added aldehyde solution. The mixture was then brought to approx. Cooled 60 ° C, and mixed with 102 g of urea and the pH the mixture was adjusted to 5.5 with formic acid. After a Residence time of 30 min under these conditions was the Mixture added a further 102 g of urea and the pH value 7.0 increased. After a further 30 minutes, components (b), (c) and (d) 8 g melamine, 17 g dicyandiamide and 33 g diethylene glycol admitted. After dissolving the three last added substances, which takes a maximum of 20 minutes, the pH of the mixture has been reduced to approx. Set 8.0 and the mixture after filtration to about 20 ° C. cooled, the operations mentioned after the addition of the Components (b) to (d) were carried out as quickly as possible, that they were finished within 20 minutes. The yield was approx.1.660 g.

Resin mixture 2

A mixture of 700 g of a 40% by weight formaldehyde solution and 262 g of urea was reacted at a pH of approximately 7.0 for 20 minutes. The pH was then reduced to approximately 5.0 and the reaction was continued at a temperature of approximately 90 ° until the reaction mixture had a flow time of 16 s ^-1 determined in the Ford cup. Then, while maintaining the latter temperature, 283 g of a 40% by weight aqueous form of aldehyde solution were added. The mixture was then cooled to about 60 ° C., 196 g of urea were added and the pH of the mixture was adjusted to 5.5 using formic acid. After a residence time of 30 min under these conditions, 95 g of melamine, 95 g of dicyandiamide and 76 g of diethylene glycol were added to components (b), (c) and (d). The preparation of the resin mixture was ended in the same manner as described in the preparation of the resin mixture 1.

Resin mixture 3

The resin mixture was as in Example 3 of DE-A-33 46 679 be wrote manufactured.

Resin mixture 4

Commercial urea-formaldehyde resin (Ureccoll® 181, BASF AG) recommended by the manufacturer as a binder for nonwovens becomes.

Resin mixture 5

Commercial urea-formaldehyde resin (Urecoll® 141, BASF AG) recommended by the manufacturer as a binder for nonwovens becomes.

The properties of the resin mixtures (HM) are shown in Table 1 reproduced.

Table 1

Application properties of the resin mixtures Water thinnability

Water dilutability became immediate on the resin blends after their production (immediately) and after 1, 2 and 3 weeks Storage at a temperature of 20 ° C examined. According to the respective A sample of the resin blends with water was taken diluted to a solids content of 20% and left to stand for 4 h sen. Then it was visually assessed whether a sediment was formed  det had. Table 1 shows the earliest point in time at which the sediment occurred.

Reactivity

The resin blends were made up by adding phosphoric acid set a pH of 5.0. It was the time after the addition of phosphoric acid until the solution gels goes, determined, the gelation on a volatile Viscosity increase is recognizable. The shorter this period (Ge time), the higher the reactivity of the resin blends.

Solids content

The solids content of the aqueous solutions of the resin mixtures and the melamine-formaldehyde resin (component a) was removed by rewie gene of a sample of 1 g, which was dried for 2 hours at 120 ° C (Be in accordance with DIN 53216 or ISO / DIN 3251).

The increase in the solids content of the resin mixture in the impregnated fabric made of fibers compared to the fabrics used for this purpose before impregnation determined by the area not yet impregnated impregnated and then 2 min at 180 ° C in a Mathis Oven dried and weighed again. From the weight The difference was the percentage increase in the solids content calculated.

viscosity

The viscosity values given with the dimension mPa · s were with an Ubbelohde viscometer with a capillary III a temperature of 23 ° C determined, otherwise the in the DIN 51562, Jan. 1989, May 1985, draft Aug. 1986, measurement conditions were observed. The values obtained for the kinematic visco sity (dimension: mm² / s) was changed with the density in the dynamic Converted viscosity (dimension mPa · s). The density determination followed according to DIN 53277 (part 5).

The viscosities that are considered to be the expiry time from a Ford cup IV were correct, refer to measurements according to the regulations the DIN ISO 2431.  

Free formaldehyde content

The free formaldehyde content was determined according to de Jong, such as it in Z. Anal. Chem. Volume 281 of 1876, pages 17 to 21, be is written. The free formaldehyde is weakly al Kalische reaction conditions with an amount of sulfite, the larger than the amount of formaldehyde is reacted with an adduct Formaldehyde and sulfite is formed. Then that's about titrated liquid sulfite at weakly acidic pH, then the ge formed sulfite-formaldehyde adduct hydrolyzed and how the sulfite released is determined by titration with iodine.

Formaldehh emission

A commercially available polyester fleece with a basis weight of approx. 150 g / m² was made with a defined amount of 20% by weight aqueous solution of the respective resin mixture with a 2-roller impregnated poulard.

The impregnated polyester fleece was left in an oven for 15 minutes dried in a 180 ° C hot air stream. Use them to dry Air was passed through water-filled wash bottles to absorb the amount of formaldehyde released into the air. The The amount of formaldehyde was then calorimetrically with methyllace ton to the Japanese Law Method 112. The one so determined emitted formaldehyde content is given in mg formaldehyde per Gram of the resin mixture applied to the polyester fleece.

Application properties of the resin mixtures bonded nonwovens produced Manufacture of bonded nonwovens

30 cm × 26 cm glass wet fleece with a basis weight of 50 g / m² were passed lengthways on an endless PES screen belt a binder liquor with a solids content of 20% (one solution of the respective resin mixture diluted with water) and there after guided over a suction device. With the help of suction The amount of binder applied was liquor to about 100% by weight, based on the glass wet fleece used (corresponds to a dry application of approx. 20% by weight). The impregnated fleece was at 2 ° C at 180 ° C on PES store (which is that?) dried as a carrier in a Mathis dryer.

Tests were made from the bonded nonwovens produced in this way body (A) a size of 240 × 50 mm and test body (B) one Die-cut size 180 × 50 mm. The short ends of the test  Linge were covered with 3 cm wide crepe paper on both sides.

If a fiber orientation was discernible in the fleece, so Probably test specimens manufactured and tested, in which the fibers pa parallel to the long side of the test object as well as in where the fibers were perpendicular to the long side of the test specimen and averaged the resulting test results.

The test specimens were examined for their tensile strength. For this they were so in a tensile testing machine at the short ends excited that the distance between the fixed ends 200 mm (Test object A) or 140 mm (test object B). The test specimen was with a pull-off speed of 25 mm / min until tearing stretched. The maximum force required for this has been determined and is given in N in Table 2.

Dry strength

The test specimens (a) were prepared as described and at Stretched room temperature.

Wet strength I

The test specimens (A) were exposed to 0.1% by weight for 15 minutes before the test aqueous solution of a conventional wetting agent (Nekal BX solution) ge stored and then stretched at room temperature.

180 ° C strength

Procedure as for measuring dry strength, however the measurement was carried out in a climatic chamber at 180 ° C.

Wet strength II

Immediately before the measurement, which is the same as when measuring the dry strength, the test specimens became hot in 80 ° C for 15 min distilled water stored.

Cooking loss

The test specimens were dried at 110 ° C. for 10 minutes, weighed and put on then stored in hot water at 100 ° C for 10 min. After that the test specimens dried at 110 ° C for 1 h and weighed again. The in % loss in weight of the test specimen is the cooking loss.

The test results of the respective resin mixtures provided nonwovens are shown in Table 2.  

Table 2

Claims (10)

1. Resin mixtures containing

• (a) 55 to 98.8% by weight of a urea-formaldehyde resin,
• (b) 0.1 to 20% by weight of melamine,
• (c) 0.1 to 20% by weight of dicyandiamide and
• (D) 1 to 30 wt .-% of an aliphatic C₂- to C Alk-alkanol with at least two alcoholic hydroxyl groups (polyol A) or at least two alcoholic hydroxyl-containing ether, composed of 2 to 10 units derived from the polyol A.

2. Resin mixtures according to claim 1, comprising as component (a) a urea-formaldehyde resin

• (a1) urea and
• (a2) 0.5 to 2.5 moles of formaldehyde per mole of urea.

3. Resin mixtures according to claim 1 or 2, containing as a compo nente (a) a urea-formaldehyde resin, which, based on a 60 wt .-% aqueous solution, a viscosity of 30 to 100 mPa · s. 4. Resin mixtures according to claims 1 to 4, containing as component (d) glycerol or a compound of general formula I. in the
R¹ is hydrogen or methyl and
n means 1 to 10. 5. Aqueous solutions containing 40 to 80% by weight of the resin mixtures according to claims 1 to 4. 6. Process for the production of bound sheets Base of fibers, characterized in that one Fabric based on fibers with the aqueous solution impregnated according to claim 5 and then ent distant. 7. The method according to claim 6, characterized in that it consists of glass fibers, mineral fibers, polyester fibers, Ceramic or cellulosic fabric acts. 8. The method according to claim 6 or 7, characterized in that the sheet is based on fibers with such a Amount of the aqueous solution impregnated according to claim 5 that the solids content of the bound compared to Fabric based on fibers before impregnation 10 to 30% increased. 9. Bound fabrics based on fibers, available according to claims 6 to 8. 10. Use of fabrics based on fibers according to An saying 9 as an inliner in bituminized roofing membranes and flooring as filter material or as battery separators.