Aqueous binder compositions of aliphatic or cycloaliphatic dicarboxaldehydes and resorcinol

Abstract

The present invention provides substantially formaldehyde free aqueous thermosetting binder resins from resorcinol and cycloaliphatic dialdehydes, glutaraldehyde or their mixtures and urea which may be excluded or included up to amounts which deter hot wet tensile strength in the cured binder. The compositions provide binders that on a performance cost basis are equivalent to phenol formaldehyde resins but without the formaldehyde.

Claims

1. A substantially formaldehyde free thermosetting binder composition that is free from added formaldehyde and phenol formaldehyde resins and which does not liberate substantial formaldehyde as a result of drying and/or curing, the composition comprising resorcinol dialdehyde resin from (i) resorcinol and (ii) one or more dialdehyde selected from the group consisting of cyclohexane dicarboxaldehyde, glutaraldehyde, and their mixtures and, further comprising an epoxy functional hydrolysable silane in the amount of from 0.3 to 1.5 wt.%, based on total resin composition solids, the compositions comprising aqueous or non-aqueous systems, wherein in the compositions, the ratio of the number of hydroxyl equivalent groups of the resorcinol to the number of aldehyde equivalent groups of the one or more dialdehyde ranges from 1:1 to 4:1, and, further, wherein when the (ii) one or more dialdehyde is glutaraldehyde the composition further comprises (iii) urea in the amount of from 0 to 10 moles urea per mole of glutaraldehyde.

2. The composition as claimed in claim 1, wherein the dialdehyde is a cyclohexane dialdehyde selected from the group consisting of cis-1,3cyclohexane dicarboxaldehyde, a trans-1,3 cyclohexane dicarboxaldehyde, a cis-1,4cyclohexane dicarboxaldehyde, a trans-1,4 cyclohexane dicarboxaldehyde, and mixtures of any two or more thereof and dissolved in water in presence of resorcinol.

3. The composition as claimed in claim 1, further comprising a base catalyst, the equivalent ratio of hydroxy groups in the base catalyst to the hydroxy groups which are present in the aqueous mixture of resorcinol and dialdehyde ranges from 0:1 to 0.28:1.

4. The composition as claimed in claim 1, comprising resorcinol dialdehyde resin from the (i) resorcinol, the (ii) one or more dialdehyde (iii) urea and (iv) base.

5. The composition as claimed in claim 1, wherein the number of hydroxyl equivalent groups of the resorcinol to the number of aldehyde equivalent groups of the one or more dialdehydes ranges from 1:1 to 3:1.

6. The composition as claimed in claim 1, wherein the epoxy functional hydrolysable silane is 3-glycidoxypropyl trimethoxy silane.

7. The composition as claimed in claim 1, wherein the binder composition is an aqueous binder composition or a binder composition powder.

8. A method of making a substantially formaldehyde free thermosetting binder composition that is free from added formaldehyde, are free from added phenol formaldehyde and which do not liberate substantial formaldehyde as a result of drying and/or curing, the method comprising reacting an aqueous mixture of (i) resorcinol and (ii) one or more dialdehyde selected from the group consisting of cyclohexane dicarboxaldehyde, glutaraldehyde, and their mixtures in the presence of a hard base catalyst to form a resorcinol dialdehyde resin, wherein the ratio of the number of hydroxyl equivalent groups of the resorcinol to the number of aldehyde equivalent groups of the one or more dialdehyde ranges from 1:1 to 4:1, and, further comprising including in the composition an epoxy functional hydrolysable silane in the amount of from 0.3 to 1.5 wt.%, based on total resin composition solids.

9. The method as claimed in claim 8, wherein the aqueous mixture further comprises (iii) urea.

Description

EXAMPLES

(1) The following examples serve to better illustrate the invention, which is not intended to be limited by the examples.

(2) Binder Preparation: In a 250 ml beaker equipped with a magnetic stirrer the desired amount of resorcinol (Sigma Aldrich, St. Louis, Mo.) was dissolved in deionized water. If the composition had urea in it, then the desired amount of urea was added under stirring at this point of time. The endothermic nature of reaction tends to cool down the solution so enough time (10-15 min) was allowed for the solution to warm up to room temperature. About 10 wt. % (Equiv ratio of base to resorcinol OH=0.07:1) based on the amount by weight of resorcinol indicated in Table 1, below, of 50% aqueous sodium hydroxide solution (Sigma Aldrich) was added with the desired amount of 3-(glycidyloxypropyl) trimethoxysilane (Sigma Aldrich) under stirring. After 5-10 min of mixing, the amount of dialdehyde indicated in Table 1, below, was added with stirring.

(3) Treatment of Glass Microfiber Filter Paper and Tensile Testing: Binders as shown in Table 1, below, were prepared by mixing the components as described in binder compositions preparation procedure, above, to provide aqueous solutions at 30 wt. % solids.

(4) TABLE-US-00001 TABLE 1 Binder Compositions Eq ratio of OH's Amt of of Resorcinol to Amt. of Amt. of Amt of Amt of NaOH (g) Amt of aldehyde group Resorcinol Dialdehyde Urea Silane (50 wt % Water Example Composition of dialdehyde (g) (g) (g) (g) aq.) (g) 1 Resorcinol:CHDA 2:1 40 25.45 0 0 4 156 2 Resorcinol:CHDA 2:1 40 25.45 0 0.34 4 156 3 Resorcinol:CHDA 2:1 40 25.45 0 0.68 4 156 4 Resorcinol:CHDA 2:1 40 25.45 0 1.01 4 156 5 Resorcinol:CHDA 2:1 40 25.45 0 1.35 4 156 6 Resorcinol:Glut.sup.1 2:1 40 36.36 0 0 4 120 7 Resorcinol:Glut.sup.1 2:1 40 36.36 0 0.30 4 120 8 Resorcinol:Glut.sup.1 2:1 40 36.36 0 0.60 4 120 9 Resorcinol:Glut.sup.1 2:1 40 36.36 0 0.90 4 120 10 Resorcinol:Glut.sup.1 2:1 40 36.36 0 1.20 4 120 11* Resorcinol:Phthal 2:1 30 18.29 0 0 3 115 12* Resorcinol:Phthal 2:1 30 18.29 0 0.25 3 115 13* Resorcinol:Phthal 2:1 30 18.29 0 0.5 3 115 14* Resorcinol:Phthal 2:1 30 18.29 0 0.75 3 115 15* Resorcinol:Phthal 2:1 30 18.29 0 1.00 3 115 16 Resorcinol:CHDA 2:1 20 12.72 21.84 0.56 2 130 17* Resorcinol:CHDA 2:1 20 12.72 43.68 0.78 2 182 18* Resorcinol:CHDA 2:1 10 6.36 32.76 0.49 1 117 19 Resorcinol:Glut.sup.1 2:1 22 20 24.02 0.57 2.2 123 20 Resorcinol:Glut.sup.1 2:1 16.5 15 36.03 0.60 1.65 135 21 Resorcinol:Glut.sup.1 2:1 13 11.81 42.58 0.62 1.3 140 22* Resorcinol:Phthal 2:1 20 12.19 21.84 0.55 2 129 23* Resorcinol:Phthal 2:1 15 9.14 32.76 0.58 1.5 135 24* Resorcinol:Phthal 2:1 10 6.09 32.76 0.49 1 116 25 Resorcinol:CHDA 1:1 25 31.81 0 0.58 2.5 136 26 Resorcinol:CHDA 1:1 15 19.09 32.76 0.67 1.5 158 27 Resorcinol:CHDA 1:1 10 12.72 43.68 0.67 1 156 28* Resorcinol:CHDA 1:1 5 6.36 32.76 0.44 0.5 104 29 Resorcinol:Glut.sup.1 1:1 30 54.54 0 0.59 3 120 30 Resorcinol:Glut.sup.1 1:1 15 27.27 32.76 0.62 1.5 120 31 Resorcinol:Glut.sup.1 1:1 10 18.18 43.68 0.63 1 120 32 Resorcinol:Glut.sup.1 1:1 7.5 13.63 49.14 0.64 0.75 120 33* Resorcinol:Phthal 1:1 25 30.48 0 0.58 2.5 115 34* Resorcinol:Phthal 1:1 15 18.29 32.76 0.67 1.5 115 35* Resorcinol:Phthal 1:1 10 12.19 43.68 0.67 1.0 115 36* Resorcinol:Phthal 1:1 5 6.09 32.76 0.44 0.5 115 37 Resorcinol:CHDA 2:1 40 25.45 0 0.68 0 156 38 Resorcinol:CHDA 2:1 40 25.45 0 0.68 0.8 156 39 Resorcinol:CHDA 2:1 40 25.45 0 0.68 1.2 156 40 Resorcinol:CHDA 2:1 40 25.45 0 0.68 2 156 41 Resorcinol:CHDA 2:1 40 25.45 0 0.68 8 156 42 Resorcinol:CHDA 2:1 40 25.45 0 0.68 16 156 *denotes Comparative Example; .sup.150 wt. % solution in water

(5) Test Methods: The following test methods were used to evaluate the binder compositions of the present invention.

(6) Tensile Testing: A binder impregnated microfiber filter (Whatman International Inc., Maidstone, England, GF/A, catalog No. 1820 866), in 20.3 cm25.4 cm sheets was prepared by drawing a filter sheet through a trough filled with 120 grams of a 30 wt.

(7) binder composition solution in water. Sandwiching the soaked sheets between two cardboard sheets to absorb excess binder, and pressing between the two cardboard sheets in a Birch Bros. Padder, 68.9476 kPa/speed 5 m/min. The resulting samples are dried @90 C. for 90 seconds in a Mathis Oven that is vented or equipped with a devolatilizer. The dried sheets were then cured at 210 C. for 180 seconds in the same type of Mathis oven used to dry the samples. Post curing weight was determined to calculate binder add-on (cured binder weight as a percentage of filter paper weight). Add on is the wt. % based on filter sheet weight of binder solids retained on the filter sheet after curing.

(8) The cured sheets were cut into 2.54 cm (1 inch) (cross machine direction) by 10.16 cm (4 inch) (machine direction) strips and tested for tensile strength in the machine direction in a Thwing-Albert Intelect 500 tensile tester. The fixture gap was 5.08 cm (2 inches) and the pull rate was 2.54 cm (1 inch)/minute. Strips were tested either as is (Dry Tensile) or immediately after a 10 minutes soak in water at 80 C. (10 min Hot Wet Tensile). Tensile strengths were recorded as the peak force measured during parting and reported in newtons. Data reported are averages of 10 test strips and are presented in Tables 2, 3, and 4, below.

(9) Acceptable dry tensile strength is >25N. The preferred dry tensile strength is >45 N. Acceptable wet tensile strength is >3N, or, preferably, >6N. Acceptable tensile strength retention (wet/dry) is >10% or an absolute measure of 3N or more. The preferred tensile strength retention (wet/dry) is >30%.

(10) Post curing weight was determined to calculate binder add-on (cured binder weight as a percentage of filter paper weight). Add on is the wt. % based on filter sheet weight of binder solids retained on the filter sheet after curing.

(11) The abbreviations used in the Tables below include: Glut: Glutaraldehyde, Phthal: Phthalic dialdehyde; CHDA: Cyclohexane dicarboxaldehyde.

(12) TABLE-US-00002 TABLE 2 Tensile Strength Data Eq ratio of OH Mols of Dry Hot-wet Tensile group Resorcinol to Urea per Tensile Tensile Strength Aldehyde group mol of Silane Strength Strength Retention Wt. % Example Composition of dialdehyde dialdehyde (wt. %) (N) (N) (%) add on 1 Resorcinol:CHDA 2:1 0 0 55.856 5.760 10.31 58.01 2 Resorcinol:CHDA 2:1 0 0.5 59.864 40.946 68.40 55.47 3 Resorcinol:CHDA 2:1 0 1 63.125 53.125 84.16 57.80 4 Resorcinol:CHDA 2:1 0 1.5 60.571 59.032 97.46 58.16 5 Resorcinol:CHDA 2:1 0 2.0 59.846 59.606 99.59 58.89 6 Resorcinol:Glut 2:1 0 0 72.795 10.498 14.42 61.20 7 Resorcinol:Glut 2:1 0 0.5 78.129 63.507 81.29 60.77 8 Resorcinol:Glut 2:1 0 1 70.829 63.863 90.17 61.74 9 Resorcinol:Glut 2:1 0 1.5 73.627 67.404 91.55 62.86 10 Resorcinol:Glut 2:1 0 2.0 72.021 68.952 95.74 62.20 11* Resorcinol:Phthal 2:1 0 0 23.687 0.000 0.00 13.22 12* Resorcinol:Phthal 2:1 0 0.5 23.144 0.000 0.00 13.23 13* Resorcinol:Phthal 2:1 0 1 21.200 0.000 0.00 13.39 14* Resorcinol:Phthal 2:1 0 1.5 24.020 0.000 0.00 13.90 15 Resorcinol:Phthal 2:1 0 2.0 21.618 0.000 0.00 13.58 *denotes Comparative Example

(13) TABLE-US-00003 TABLE 3 Tensile Strength Data-Effect Of Urea In 2:1 Resorcinol:Dialdehyde Mol Ratio Eq ratio of OH's Mols of Dry Hot wet Tensile of Resorcinol to Urea per Tensile Tensile Strength aldehyde group mol Silane Strength Strength Retention Wt. % Example Composition of dialdehyde Dialdehyde (wt. %) (N) (N) (%) Add On 3 Resorcinol:CHDA 2:1 0 1 63.125 53.125 84.16 57.80 16 Resorcinol:CHDA 2:1 4 1 40.523 20.057 49.50 21.74 17* Resorcinol:CHDA 2:1 8 1 23.945 2.967 12.39 12.07 18* Resorcinol:CHDA 2:1 12 1 21.383 2.349 10.98 7.62 8 Resorcinol:Glut 2:1 0 1 70.829 63.863 90.17 61.74 19 Resorcinol:Glut 2:1 4 1 49.349 47.338 95.93 24.82 20 Resorcinol:Glut 2:1 8 1 45.074 29.825 66.17 12.44 21 Resorcinol:Glut 2:1 12 1 37.881 26.614 70.26 9.35 13* Resorcinol:Phthal 2:1 0 1 21.200 0.000 0.00 13.39 22* Resorcinol:Phthal 2:1 4 1 10.049 0.000 0.00 3.84 23* Resorcinol:Phthal 2:1 8 1 8.114 0.000 0.00 3.32 24* Resorcinol:Phthal 2:1 12 1 9.368 0.000 0.00 3.09 *denotes Comparative Example

(14) TABLE-US-00004 TABLE 4 Tensile Strength Data--Effect Of Urea In 1:1 Resorcinol:Dialdehyde Mol Ratio Eq ratio of OH's Mols of Dry Hot Wet Tensile of Resorcinol to Urea per Tensile Tensile Strength aldehyde group mol of Silane Strength Strength Retention Wt. % Example Composition of dialdehyde Dialdehyde (wt. %) (N) (N) (%) Add On 25 Resorcinol:CHDA 1:1 0 1 58.579 47.979 81.90 53.46 26 Resorcinol:CHDA 1:1 4 1 30.030 5.360 17.85 14.90 27 Resorcinol:CHDA 1:1 8 1 23.100 5.098 22.07 9.22 28* Resorcinol:CHDA 1:1 12 1 20.907 2.931 14.02 8.05 29 Resorcinol:Glut 1:1 0 1 66.692 65.340 97.97 ?55.35?? 30 Resorcinol:Glut 1:1 4 1 47.738 44.069 92.31 16.99 31 Resorcinol:Glut 1:1 8 1 38.161 30.617 80.23 10.29 32 Resorcinol:Glut 1:1 12 1 30.461 20.048 65.81 7.72 33* Resorcinol:Phthal 1:1 0 1 12.820 0.000 0.00 10.17 34* Resorcinol:Phthal 1:1 4 1 7.896 0.000 0.00 3.44 35* Resorcinol:Phthal 1:1 8 1 9.346 0.000 0.00 2.98 36* Resorcinol:Phthal 1:1 12 1 7.953 0.000 0.00 2.59 *denotes Comparative Example

(15) As shown in Tables 2, 3 and 4, above, the inventive substantially formaldehyde free binder compositions all retain at least 10 wt. % of their dry tensile strength when wet or provide acceptable hot wet strength, unless the amount of urea exceeds the inventive limits and/or there is insufficient silane to counter the adverse impact of the urea. The Example 17 resorcinol dialdehyde resin with 4 moles urea per mole of dialdehyde demonstrates a performance just below the lower limits of the performance of the inventive compositions.

(16) In all the binder compositions in Examples 1-36, the amount of catalyst, based on the amount of resorcinol, was maintained at about 5 wt. % of NaOH (or equivalent ratio io of hydroxy groups in the base catalyst to the hydroxy groups 0.069:1, like in Example 3). The gelation time is defined as the time taken after adding all the ingredients before forming a hard gel at room temperature. An acceptable gelation time is 30 minutes or more for binder compositions that are used directly after they are made, and is 2 weeks or more for binder compositions that are to be shipped. Table 5, below, shows the relationship between amount of base and gelation time. Adding organic solvents can increase the gelation time.

(17) TABLE-US-00005 TABLE 5 Cure Speed As Function Of Amount Of NaOH Equivalent ratio of OH groups in the base catalyst to OH groups in Example Composition the binder Gelation time 37 Resorcinol:CHDA 0:1 38 Resorcinol:CHDA 0.014:1 2 weeks 39 Resorcinol:CHDA 0.028:1 1-2 week 40 Resorcinol:CHDA 0.034:1 5-6 days 3 Resorcinol:CHDA 0.069:1 3 days 41 Resorcinol:CHDA 0.138:1 60 min *42 Resorcinol:CHDA 0.275:1 <30 min *denotes Comparative Example

(18) As shown in Table 5, above, less than 20 wt. % of base (or equivalent ratio of hydroxy groups in the base catalyst to the hydroxy groups 0.275:1) based on the total solids weight of resorcinol is desirable, and less than 10 wt. % (or equivalent ratio of hydroxy groups in the base catalyst to the hydroxy groups 0.138:1) is preferred.