FI56851C - FRAMEWORK FOR FRAMSTAELLNING AV ETT MED VATTEN FOERTUNNBART POLYESTERHARTS - Google Patents

Description

I- - -'- I Γο1 NOTICE OF PUBLICATION * _ [B] (11) UTLÄGGN I NGSSKRIFT 5685 1 C (45) Patent granted 10 C4 1900 Patent meddelat ^ 'r ~~' (51) Kv.ik. * / Int .ci. «C 08 G 63/12 C 09 D 3/52 FINLAND - FINLAND (21) Patent application - Patentansttknlng 3101/72 (22) Hakemlspllvi - Anaöknlngadaf 1 ^ +. 11.72 (23) The beginning of the cloud - Glltifhetsdag 1 ^. 11.72 (41) Tullut {ulklseksl - Bllvlt offentlig 22.10.73

National Board of Patents and Registration (44) Date of issue and date of publication——

Patent · OCh registerstyrelsen AnsttkM utlagd och utl.skrlften publkerad 31.12.79 (32) (33) (31) Pyydetty etuoikeus — Begird prloritet 21.0¾. 72 USA (US) 2U6353 Proven-Styrkt (71) Whittaker Corporation, IO88O Wilshire Boulevard, Los Angeles,

California 9002 ^ +, USA (US) (72) Edward Abe Lasher, Beverly Hills, California, USA (US) (7 * 0 Oy Kolster Ab (5 ^ +) Method for preparing a water-thinnable polyester resin -Förfarande för framställning av ett med vatten This invention relates to the preparation of a water-thinnable polyester resin which can be used with an amino resin as a wood coating material.

Due to the growing shortage of hardwood species such as walnut and oak, there is a growing tendency to make wood fiber panel by coating cheap wood materials such as plywood and masonite with an organic coating resembling wood fibers. This method involves forming a base coat on e.g. a plywood panel, usually after it has been filled, printing a desired wood fiber pattern on that base coat and then forming a surface coating to protect the wood fiber pattern.

Currently used base and surface coatings are usually formed of polyester which is reacted with an amino or similar resin. However, these coatings are formed from the above ingredients using substantial amounts of solvents other than water. The amount of such solvents 2 56851 may be considerable. For example, as much as 2 tons of solvent can be used to make k 500 l of coating material. Since most of this solvent is lost during or after manufacture as the coating dries, a considerable amount of impurity is caused as these vapors evaporate into the atmosphere. For this reason, it is desirable to replace substantially all previously used solvents with water.

In addition to the desirability of using thermosetting, aqueous resin solutions, it is desirable to add water-soluble aminoplast resins, e.g., urea-formaldehyde resins, to such solutions because the latter harden to form hard water-insoluble coatings. However, cured aminoplastic resins are brittle or crumbly without modification. For this reason, they are unsuitable without modification for use for purposes where flexibility is required, especially if significant temperature variations still occur.

To date, polyester-modified aminoplastic resin coatings have been prepared as disclosed in, e.g., U.S. Patents 3,777,976, 3,223,666, and 3,108,083.

However, these coatings have the disadvantage that the amount of polyester resin present in these coatings is considerably higher than that of the amino resin. As typical weight ratios of polyester and aminoplastic resin, ratios range from 3: 1 to 10: 1. The low amounts of amino resin used mean that the advantageous properties of these resins are significantly modified by the disadvantageous properties. In other words, the degree of curing and resistance to water and chemicals are reduced compared to the amino resin alone. In addition, costs increase due to the higher price of polyester resins.

The present invention relates to a process for the preparation of a water-thinnable polyester resin suitable for finishing wood.

The process of the invention is characterized by mixing together a polyol having a functionality of about 3 to 3.5 and a carbon / oxygen ratio of about 5: 3 to 7: 3, preferably a trio, namely trimethylolethane or trimethylolpropane, and a polycarboxylic acid having from 3 to about 10 a carbon atom, preferably orthophthalic acid, isophthalic acid, succinic acid, adipic acid or an acid-anhydride thereof in an equivalent ratio of polyol to polycarboxylic acid of about 1.9: 1-3: 1, and the mixture is heated to below the esterification reaction until heating is continued. 10.

A primary advantage of using the ester resins disclosed herein when used in conjunction with water-soluble aminoplastic resins is that they allow higher amounts of aminoplastic resins to be used in aqueous media than has been possible to date while adequately modifying the embrittlement properties of 3,5851 amino resin resins. In addition to having overall physical and chemical properties at least as good as previously used aminoplastic coatings made using organic solvents, they can be prepared with significantly less contamination than that caused by evaporation of organic solvents during curing. This is particularly significant given that, as discussed above, about 2 tons of solvent can be used to make 1 * 500 liters of water-insoluble coating, and that this amount of coating can be used on the paneling line in one day or less.

In addition, significant cost savings are achieved because water is cheaper than organic solvents. In addition, cost savings are obtained by using relatively high concentrations of aminoplastic resin, since these, in particular, more readily available urea and melamine-formaldehyde resins are cheaper than ester resins.

The coatings described herein are also characterized by rapid curing (about 1-2 minutes) to a hardness of about UH-6H at a relatively low temperature of about 66-93 ° C. This is particularly important because the panels to be coated are still stacked hot immediately after they have been removed from the paneling line. If the curing at this time is not somewhat complete, the coatings will break badly. Low curing temperatures are necessary due to the properties of the wood to be coated (higher temperatures can be used with masonite, for example).

As used herein, the phrase "water-thinnable" refers to ester resins prepared as described herein that are soluble as solutions containing at least about 10% to 10% solids in solvent mixtures containing up to about 65% (by weight) of water. In general, certain polyester coatings containing higher carbon / oxygen ratios are dilutable with water only up to the amount mentioned above, while some diesters with lower carbon / oxygen ratios are soluble in water alone up to a solids content of about 10 #. Unless otherwise indicated, all percentages used herein are by weight.

The ester resin may be a di- or triester (hereinafter referred to as a diester) or a polyester. In either case, the ester resin is prepared by reacting certain triols or their equivalents described below with a polycarboxylic acid selected for the triol so that the resulting ester is dilutable with water.

The triols used herein are solids at normal ambient temperature with a carbon / oxygen ratio of about 5: 3 to T: 3- The ester resin obtained in ratios greater than about 7 = 3 is substantially insoluble in aqueous 4 ϋοβδ1 solvent mixtures, at carbon / oxygen ratios below about 5: 3 triol, e.g. glycerol, when used in combination with aliphatic polycarboxylic acids, makes the water-insoluble product too soft to be used in wood finishing coatings. Examples of suitable triols are trimethylolethane, trimethylolpropane and trimethylolybutane.

As discussed above, equivalents of these triols can be used. By this is meant that combinations of diols and polyols, or polyols, may be used provided that the combination meets the above requirement for a carbon / oxygen ratio and has an average functionality of 3 to about 3.5. · An example of such an equivalent is a combination of neopentyl glycol and pentaerythritol used in equal molar amounts. It should be noted that neither of these alcohols alone would produce a water-insoluble coating, albeit from different eyes. Among other things, the functionality of neopentyl glycol is too low to provide sufficient crosslinking with the amino resin, and the functionality of pentaerythrotritol is high because too many hydroxyl groups remain unreacted. In both cases, the result is relatively soft, water-permeable coatings.

Hereinafter, and in the claims, the term "triol" means an alcohol combination equivalent to a triol and any triols suitable for use herein.

Polycarboxylic acids suitable for use herein may be aliphatic or aromatic and saturated or unsaturated. They may also be di-, tri- or tetrafunctional, although difunctional carboxylic acids are most preferred because they generally react more completely with the triols used herein. The acid used in each case is one which, when used in conjunction with the particular triol in question and in the amounts subsequently disclosed in this patent, produces a water-dilutable diester or polyester. To produce desters or polyesters, the polycarboxylic acid is usually selected from acids having 3 to 10 carbon atoms. In general, if a polycarboxylic acid is unsaturated, it may also contain more carbon atoms than the saturated acid to produce a water-soluble product with a given triol.

Examples of useful polycarboxylic acids are: orthophthalic acid, isophthalic acid, tetrahydrophthalic acid, terephthalic acid, hexahydrophthalic acid, endomethylenetetrahydrophthalic acid, malonic acid, succinic acid, succinic acid, glutaric acid, glutaric acid Anhydrides of these acids can also be used.

For the masters, the ratio of triol to polycarboxylic acid is about 3 equivalents per 5 g of trioxide per acid equivalent. This means that about 2 moles of trio are used per mole of dicarboxylic acid, while 3 moles of trio are used for each mole of tricarboxylic acid. Using the above equivalent ratios, at least tetrafunctional diesters are obtained. Further, the water-dilutable ester resins thus produced have a carbon / oxygen ratio of up to about 2.5: 1 ·

The polyester resin is prepared by reacting about 1.9 to 2.5 equivalents with a triol of one polycarboxylic acid equivalent.

With this ratio of triol to acid, water-thinnable polyesters also have a maximum carbon / oxygen ratio of about 2.5: 1 ·

As for both diesters and polyester, if the proportion of triol is substantially higher than shown, it has an adverse effect on the water insolubility of the coatings. On the other hand, if the proportion of polycarboxylic acid is substantially higher than indicated (corresponding to the lower proportion of triol), it has an adverse effect on the water dilutability of diester and polyester resins during the reaction so as to obtain the low acid numbers according to the patent.

To prepare diester or polyester resins, the triol and polycarboxylic acid are reacted with each other under process conditions well known in the art. Most preferably, they are reacted with each other in a reactor vessel equipped with a stirrer to mix the reactor contents to a substantially homogeneous nature, and the reaction is carried out in an inert atmosphere, e.g., carbon dioxide, heated to about 232 ° C for about 5-4 hours and maintained at that temperature. until the etherification is practically complete, i. until substantially all of the carboxyl groups have reacted with the triol hydroxyls. This is demonstrated by acid number determinations that can be performed from time to time. When the reaction is more or less complete, the acid number is less than about 10.

The diesters thus formed are better dilutable with water than polyesters * However, polyesters can be coated with a lower solids content because they have a higher natural viscosity and because they are more resistant to surface deterioration (adhesion) at high temperatures. In addition, cured coatings have somewhat lower water solubility when made from polyesters compared to those made from diesters.

To make wood finishing coatings, diesters and polyesters are reacted with water-soluble aminoplastic resins, e.g., urea-aldehyde and melamine-aldehyde resins. Most preferably, due to their good availability and lower cost, urea-formaldehyde resins are used, especially if the panel to be coated is wood, which dictates the use of a low hardener temperature. If the panel to be coated is formed of materials, e.g. masonite or hard wood species, which allow the use of relatively high curing temperatures, diesters and polyesters can be reacted with water-soluble melamine-aldehyde resins, e.g. melamine-formaldehyde resins.

The reaction between the diester or polyester and the water-soluble aminoplast resin is carried out in a solution in which the solvent is water or water together with e.g. isopropanol. This can be accomplished by dissolving the ester in water or isopropanol and then adding to the solution an amino resin dissolved in water or isopropanol so that the two reactants remain in solution in the resulting solvent composition.

The amount of urea-aldehyde or melamine-aldehyde resin used depends on the permissible curing temperature and the type of ester, i.e. whether it is diester or polyester. Higher permissible curing temperatures allow the use of lower amounts of aldehyde resin. Because of the larger size of the polyester molecules, smaller amounts of aldehyde resin are effective in combination with the polyester compared to the urea aldehyde resin, either of which can be used. In any case, the amount of aldehyde resin used is such as to produce a substantially water-insoluble cured coating. By substantial water insolubility is meant that the cured coating itself is not significantly affected by immersion in water at room temperature for several days.

The diester is usually reacted with an amount of urea-aldehyde resin such that it accounts for about 50 to 75 of the total weight of the two reactants. Smaller amounts of melamine aldehyde resin can be used with the diester. A polyurea of the urea-aldehyde resin can be used with the polyester in an amount of about 25 to 75% of the reactants, while the melamine-aldehyde resin can be used in smaller amounts.

The curing of the ester-aminoplastic reactates takes place at elevated temperatures, preferably in the presence of a catalyst such as toluenesulfonic acid (TSA). Temperatures up to about 176 ° C can be used, although the temperature used in each case is usually determined by the panel material on which the coating is made. For example, some wood panels limit the curing temperature to about 65-93 ° C, while masonite and certain hardwood panels allow temperatures up to 176 ° C. The curing time is also usually determined by the panel coating line, and is usually on the order of 1-2 minutes. Even at such short times and low curing temperatures, the coatings described herein undergo crosslinking and cure approximately completely and become substantially water impermeable and resistant to the high pressures of 7 SG8 £ 1 found in panel stacks. · The present invention is further illustrated by the following examples. Example 1

A number of diesters and one triester were prepared using the combination of triols and polycarboxylic acids of this patent as shown in Table 1 below.

The method of preparation used in each case was essentially the same and was as follows: the reactants were charged to the reactor vessel in the amounts shown in Table 1. The vessel was placed in a carbon dioxide atmosphere and held with slow heating with stirring at about 232-254 ° C for about 2; For 5 to 3 hours. This temperature was maintained for about another hour until the acid number of the solids in the reaction mixture had dropped to about 10 or less. The water formed in the condensation was removed from the reactor as it formed.

When the reaction was complete, isopropanol was added to the resulting diether to obtain the desired solids content. Each of these esters had to be diluted with water.

table 1

Resin and amount (g)

The BCDEFGH

Trimethylolpropane 1418 1346 1540 1297 1551

Trimethylolethane 1372 1297 1500

Adipic acid 773 834

Phthalic anhydride 744,800

Maleic anhydride 563 612

Trimellitic anhydride 619

Succinic anhydride 572

Solids (w / w) ——————— 80 --------------------------

Solid acid acid 4 »4 3 * 5 4 * 9 4 * 9 7 * 5 5 * 6 4 * 8 3 path

Solvent ------------- Isopropyl alcohol ----------------

Each ester resin (A-H) shown in Table 1 was used to prepare a thermosetting, aqueous resin composition (I-P, respectively). Each of these was prepared using the same concentrations and components (except ester) as shown in Table 2. Each ether resin was used as a 80 weight solution in IPA. XB-1065-25-80 is a solution of 88% (w / w) urea-formaldehyde resin in isopropanol.

Table 2 θ 56851

Component

Resin and amount (g) IJKLMNOP

Ester resin ABCDEPGH

ΧΒ-1065-25-ΘΟ ------------ 70 ----------------

Distilled water ------------ 25 ---------------- 50 weights in TSA water ------------- 5 ~ —------------ 30 g of each ester resin solution was used.

The components of each composition shown in Table 2 were heated together at 149 ° C for 10 seconds to produce a cured coating. In each case, good curing was obtained. Uncured coatings had excellent fluidity when applied to the substrate, with the same level of fluidity as in the solvent system. In all cases, the cured coatings showed excellent water resistance after standing at room temperature for a few days.

Example 2 This example illustrates the use of a combination of organic alcohols instead of the single triol used in Example 1 to prepare diester (Q) and two polyester (H and S) resins.

Ester resins were prepared as described in Example 1 using the components in the amounts shown in Table 3. Phosphoric acid was used to catalyze one of the reactions, although this was not necessary. Resins Q, R and S had a total hydroxyl functionality of about 3 * 1, respectively? 5 * 4 and 5.5.

Table 3

Component Resin and amount (g)

Q R S

Adipic acid 93-5

Phthalic anhydride

Isophthalic acid 1095

Trimethylolethane 900

pentaerythritol

Dipentaerythritol 210

Diethylene glycol

Neopentyl glycol 326

Pentek (87 ^ mono- and $ 13> 784 with dipentaerythritol)

Distilled water 22 85 io H PO 2 5 4 9

Table 3 (continued) G6851

Solids (w / w) Θ0 80 70

Acid number of solids 5 »2 3 * 7 0

Solvent IPA 50 ^ uO IPA

Dilute with water yes yes yes C / O ratio - 1 »974 2,355

Each of these resins was used to prepare a thermosetting resin solution using the components and concentrations shown in Table 4.

Table 4

Component Resin and amount (g)

T U X

Q 50 R 30 S 31.6 XB-IO65-25-8O 70 27.6 75

Distilled water 25 15 »5 25 50 io TSA in water 5 5

Isopropanol 14 »3

30 io ISA methanol solution 5 »O

Wax solution ($ 15) 6.0 149 ° c / 10 sec. good excellent good

Drinking year - —excellent ------

Excellent water resistance --------

Example 3 This example illustrates the formation of polyesters using a single trio.

The polyesters were prepared as described in Example 1 using the components and component concentrations shown in Table 5

Table 5

Component Resin and amount (g)

V W

Isophthalic acid 480 908

Trimethylolethane 1174 1150

Maleic anhydride 115 190

Adipic acid 423

Solids (w / w) 70 60

Acid number of solids 5 »8 8.35

Table 5 (continued) 10 56851

Solvent IPA 75 i »IPAj 25 # HgO

Water Dilutable Yes Yes C / O Ratio 2.24 2.228 Thermosetting resin compositions were prepared from fermented polyesters as described in Example 1 using the components and concentrations shown in Table 6.

Table 6

Component Resin and amount (g)

Y Z

V 51.6 W 36.8 XB-1065-25-80 27.6 27.6

Isopropanol 14.3 11.5

Distilled water 15.5 13.1 50 io TSA isopropanol s 5 5

Wax solution (15 6 6

Curing ----— Excellent ------

Water seeping through ——— likewise --- ——

Drowsiness ——--- as well as --------—

Adhesion to the base layer ——--- as well as ---—-——

The compositions shown in Table 6 were cured at 149 ° C * for 30 seconds, and the results are shown in Table 6. The water resistance of both cured resins after several days at room temperature was excellent.

Claims (3)

56851 A process for preparing a water-thinnable polyester resin suitable for finishing wood, characterized in that a polyol having a functionality of about 3-3.5 and a carbon / oxygen ratio of about 5: 3-7: 3, preferably a triol, namely trimethylolethane, is mixed together or trimethylolpropane, and a polycarboxylic acid having 3 to about 10 carbon atoms, preferably orthophthalic acid, isophthalic acid, succinic acid, adipic acid, or anhydride of such an acid, to provide a polyol to polycarboxylic acid equivalent ratio of about 1.9: 1-3: , continuing the heating until the acid number of the ester resin is less than about 10. Process according to Claim 1, characterized in that a diester resin is formed and in that the ratio of polyol / polycarboxylic acid equivalents is about 3: 1. Process according to Claim 1, characterized in that a polyester resin is formed and in that the ratio of polyol / polycarboxylic acid equivalents is about 1.9: 1 to 2.5: 1 ·