Eastman triangle glycol study

Transcription

1 Eastman triangle glycol study HDM MPD eopentyl family glycol H 3 HO H 2 H 2 OH ycloaliphatic Family HDM glycol H 2 OH H 3 IUPA 2,2-dimethyl-,3-propanediol MPD glycol H 3 H 3 H 2 OH IUPA,-cyclohexanedimethanol H 3 H H H 2 OH OH H 3 IUPA 2,2,-trimethyl-,3-pentanediol

2 Eastman triangle glycol study (ontinued) Introduction A key application for our glycols is in saturated polyesters for coatings. he influence of Eastman, Eastman MPD, and Eastman HDM glycols on resin and coating properties was investigated through the use of a statistically designed study. he results are described in this publication. For many years, Eastman has described the performance offered by its line of polyester intermediates through their structure/property relationship. A basic structural comparison of these 3 glycols is shown in able. able Structural comparison of Eastman glycols MPD HDM Structure type Aliphatic Aliphatic ycloaliphatic Hydroxyl types 2 Primary Primary Secondary 2 Primary Hydroxyl orientation,3,3,6 Experimental details he method of investigation chosen to study these glycols was a statistically designed mixture experiment. 2 he study was based on a typical high-solids resin composition. he design of the experiment is shown in Figure with a dot representing each resin included in the study. A dot at the corner of the triangle indicates 00% usage of the glycol in the resin, while a dot at the midpoint of a triangle leg represents : molar blend of those two glycols. he dot at the center of the triangle means equal molar amounts (::) of all 3 glycols were used in the resin. he total high-solids resin compositions and resin property boundaries are described in able 2. All resins were cooked to similar acid numbers, molecular weights, and hydroxyl numbers (see able 3). Figure Experimental design Steric hindrance 2 Me 2 Me i-pr yclohexane ring HDM MPD Eastman Publication Eastman Publication Eastman Publication -323 Eastman Publication -327 Eastman Publication

3 Eastman triangle glycol study (ontinued) able 2 Resin compositions and properties Resin compositions Resin properties Moles Glycols 2.97 rimethylolpropane a 0.27 Eastman,-HDA 0.67 Eastman purified isophthalic acid (PIA) 0.67 Adipic acid 0.67 Final acid number, mg KOH/g resin Molecular weight (Mn by GP) Hydroxyl number, mg KOH/g resin Wt% solids in xylene 7 80 a wo-stage addition of trimethylolpropane able 3 Resin summary Resin composition Resin properties Eastman glycol Eastman MPD glycol Eastman HDM glycol Mn OH# A g he resulting 7 resins were formulated into typical white enamels per able. Additional solvent blend was added to each enamel to obtain a viscosity of seconds (# Ford cup). he enamels were sprayed onto Bonderite 37 pretreated 20-gauge, cold-rolled steel test panels and were baked to a similar degree of cure as measured by MEK double rubs to mar (range = 0 80) to obtain a cured film thickness of.7 2. mils. able Enamel formulation Ingredients Wt% Polyester resin (calculated 8 wt%.v.) 2.8 ymel 303 melamine resin a 2.2 i-pure R-900 io 2 pigment b 32. p-oluenesulfonic acid catalyst (0 wt%.v.) 0. Fluorad F-30 flow control additive c 0. (20 wt%.v.) Solvent blend d Pigment:binder weight ratio 0:60 Polyester:melamine weight ratio 7:2 a ytec b DuPont c 3M ompany d Eastman MAK/Eastman EEP n-butyl alcohol in a weight ratio of :: 3

4 Eastman triangle glycol study (ontinued) Results interpretation and index he results obtained through the determination of various resin and enamel properties were used to generate numerous contour maps. Regression analysis was used to interpret the data. An example of one such contour map is shown in Figure 2. One additional and very desirable piece of information can be gained through the use of statistically designed mixture experiments the occurrence of synergism and/or antagonism. Synergism occurs when one obtains betterthan-expected results when combining components. Antagonism occurs when one obtains worse-thanexpected results when combining components. Synergism is what every experimentalist hopes to obtain but can never predict. he symbols (used as superscripts) shown in the following are used throughout this text to indicate the presence of synergism or antagonism for a given performance property. Look for these important features. Symbol key +/S = Synergism /A = Antagonism Desired = HDM = = MPD Figure 2 Process time in hours Undesired he trends generated from this information will be shown on a horizontal line with the desired performance on the left and the undesired performance on the right. he performance of each glycol is designated by the first letter of its name (i.e., for Eastman glycol). he overall performance is obtained by averaging all the evaluations in the given category. he purpose of this form of data presentation is to compare the performance of one glycol to another and not to indicate that one glycol is good while another is bad. It is suggested that Eastman glycol be used as a reference point because most of the coatings industry is familiar with its performance in various applications. Users should take careful note of the range of performance differences and determine for themselves whether the range is wide enough to justify changing the resin glycol composition for a specific application. he performance categories investigated are shown in able. able Performance Performance property Page Processability ure response 6 Volatile Organic ompound (VO) 6 Viscosity 7 Hardness 8 Flexibility 9 Stain resistance 0 Detergent resistance leveland humidity 2 Salt spray 3 Summary HDM MPD

5 Eastman triangle glycol study (ontinued) Processability he cycloaliphatic structure of Eastman HDM appears to offer increased reactivity of its primary hydroxyl groups relative to the primary hydroxyl groups of Eastman glycol. he cyclohexane ring must minimize steric interference of the hydroxyl groups making them readily accessible for reaction. he combination of one secondary hydroxyl group and a high degree of steric shielding of the hydroxyls significantly decreases the reaction rate of Eastman MPD glycol relative to other glycols. Process time, h Organic distillate a water-insoluble wt% loss HDM MPD Resin color APHA 0 2 Process time, h / Resin color a APHA HDM MPD a Eastman MPD can dehydrate during resin synthesis giving small amounts of water-insoluble rearrangement products in the distillate. hese rearrangement products also add to resin color ote: Symbol definition key on page. Overall

6 Eastman triangle glycol study (ontinued) ure response he cycloaliphatic structure of Eastman HDM with its readily accessible hydroxyl groups clearly provides for a rapid cure response with crosslinking resins as compared to the other glycols. his is consistent with the processability performance definition (page ). Surprisingly, Eastman MPD glycol shows no significantly slower cure response as compared to Eastman glycol in this study. ote that a : combination of HDM and MPD shows a significant decrease in cure time. VO o significant difference in volatile organic compound (VO) was observed between Eastman and Eastman MPD glycols; however, it has been demonstrated through countless commercial resins that MPD glycol yields lower VO coatings, due to its bulky asymmetrical structure. he cycloaliphatic structure of Eastman HDM provides for close packing of the polymer chains and a high degree of hydrogen bonding between chains. his results in higher solution viscosities of the resins and VOs of the coatings. ure time min at 63 (32 F) VO at 9 (300 F) for 20 min, g/l (lb/gal) g/l (2.8) 37 g/l (3.0) ote: Symbol definition key on page. ote: Symbol definition key on page. ure time min at 63 (32 F) VO at 9 (300 F) for 20 min, g/l (lb/gal) 333 (2.8) (2.9) (3.0) HDM MPD HDM MPD 6

7 Eastman triangle glycol study (ontinued) Viscosity Eastman and Eastman MPD glycols gave very similar results in terms of both neat and solution viscosities of the resins. Look at each performance definition separately to obtain a greater degree of differentiation of these glycols. he,-cycloaliphatic structure of Eastman HDM (as compared to the aliphatic structure of the other glycols) gave significantly higher viscosity resins. Gardner at 70% solids Gardner viscosity at 70 wt% solids P R V L HDM MPD L W Brookfield at 70% solids mpa s II viscosity at 00, Pa s II at 00 Pa s HDM MPD Overall ote: Symbol definition key on page. 7

8 Eastman triangle glycol study (ontinued) Hardness he,-orientation about its cyclohexane ring results in Eastman HDM giving the hardest film of the glycols evaluated in this study. ote the opportunity for improvement (synergism) by combining Eastman and Eastman MPD glycols properly. Pencil hardness to mar Pencil to mar + + 2H H 2H ukon knoops + F + 2H HDM MPD Overall ukon hardness knoops ote: Symbol definition key on page HDM MPD 8

9 Eastman triangle glycol study (ontinued) Flexibility Eastman MPD glycol is clearly the least flexible of the glycols evaluated in this study. ote the synergism in the reverse impact resistance evaluation. onical Mandrel % pass onical Mandrel % pass 00 Impact resistance forward, m a HDM MPD Impact resistance reverse, m (in.-lb) Impact resistance reverse, m a (20) Overall 3.6 (20).3 (00) 9.0 (80) 6.8 (60) HDM MPD a ewton meter ote: Symbol definition key on page. 9

10 Eastman triangle glycol study (ontinued) Stain resistance A wide variety of results were obtained from one stain test to another. his resulted in a bunching in the overall performance. It is suggested that the formulator look at the specific test that matches the application. Stain resistance mustard, 2 h, uncovered Iodine, 30 min covered Lipstick, 2 h covered Mustard, 2 h covered HDM MPD Stain resistance lipstick, 2 h, covered Mustard, 2 h uncovered HDM MPD Overall ote: Symbol definition key on page. 0

11 Eastman triangle glycol Study (ontinued) Detergent resistance he five-day detergent resistance results show that Eastman HDM, followed by Eastman MPD glycol, provides films with the best overall performance of the glycols evaluated in this study. he higher g of HDM systems and the steric shielding of MPD glycol are possible reasons for these results. Detergent resistance 60 gloss retention, % Gloss retention, % HDM MPD Blistering a size + + Detergent resistance blistering, frequency Blistering a frequency one Dense Overall HDM MPD a ASM D7 ote: Symbol definition key on page. ASM D228-73

12 Eastman triangle glycol study (ontinued) leveland humidity he results for the leveland humidity test (2000 h at 60 [0 F]) show that cycloaliphatic Eastman HDM clearly outperforms the aliphatic glycols ( and MPD glycols). his strongly suggests the higher g (averaging higher compared to resins containing no HDM) of the cycloaliphatic containing resins is a very important factor in this performance characteristic. leveland humidity 20 gloss retention, % Gloss retention, % HDM MPD Blistering a size leveland humidity blistering, size Blistering a frequency one Overall Dense HDM MPD a ASM D7 ote: Symbol definition key on page. ASM D8 2

13 Eastman riangle glycol Study (ontinued) Salt spray he 000-hour salt spray test results show that the cycloaliphatic structure of Eastman HDM gives films with the best resistance to creepage from the scribe. reepage mm + + Summary he trends shown following the summary can be used by the resin chemist to make the best first choice of glycols to be selected for a new resin or resin improvement. his information should better define the performance properties imparted to resins and coatings by these glycols (relative to each other). Understanding the structure/property relationships of these glycols makes it easier to design resins for specific end-use applications. 0 Salt spray reepage, mm 2.7 oated samples were subjected to accelerated weathering via EMMAQUA (2 months), QUV-A (2300 hours), and natural weathering in Florida ( South, Black Box, 2 months). Results were not statistically significant and therefore are not included here. he following are some generalized statements about each of the Eastman glycols: HDM MPD ASM B7-6 ote: Symbol definition key on page. Eastman glycol: A well-known industry standard for many applications (appliance, coil, powder, etc.); very good overall performance; used as the key reference point with which the other glycols in this study were compared. Eastman MPD glycol: First choice commercially for highest-solids applications due to bulky structure; steric shielding of the hydroxyl groups provides for good hydrolytic stability and stain resistance; slowest to process; poor hardness/flexibility ratio. Eastman HDM: Only Eastman glycol with the unique cycloaliphatic structure yields higher g resins than aliphatic glycol-based resins; offers good salt spray, leveland humidity and detergent resistance; cycloaliphatic structure gives best hardness/flexibility ratio; fastest processing and curing glycol; main disadvantages are high solution viscosity and VO. 3

14 Eastman triangle glycol study (ontinued) Processability S/A Flexibility S ure response Stain resistance VO Detergent resistance S/A Viscosity leveland humidity S Hardness S Salt spray S ote: Symbol definition key on page.

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