WO1993008954A1 - Blast cleaning method and composition - Google Patents
Blast cleaning method and composition Download PDFInfo
- Publication number
- WO1993008954A1 WO1993008954A1 PCT/GB1992/002041 GB9202041W WO9308954A1 WO 1993008954 A1 WO1993008954 A1 WO 1993008954A1 GB 9202041 W GB9202041 W GB 9202041W WO 9308954 A1 WO9308954 A1 WO 9308954A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- resin
- heat
- urea
- composition
- formaldehyde
- Prior art date
Links
- 238000004140 cleaning Methods 0.000 title claims abstract description 17
- 238000000034 method Methods 0.000 title claims abstract description 17
- 239000000203 mixture Substances 0.000 title claims description 21
- 239000002245 particle Substances 0.000 claims abstract description 28
- 229920005989 resin Polymers 0.000 claims abstract description 28
- 239000011347 resin Substances 0.000 claims abstract description 28
- 229920001187 thermosetting polymer Polymers 0.000 claims abstract description 4
- 239000004634 thermosetting polymer Substances 0.000 claims abstract description 4
- WSFSSNUMVMOOMR-UHFFFAOYSA-N Formaldehyde Chemical compound O=C WSFSSNUMVMOOMR-UHFFFAOYSA-N 0.000 claims description 15
- 229920001807 Urea-formaldehyde Polymers 0.000 claims description 11
- GZCGUPFRVQAUEE-SLPGGIOYSA-N aldehydo-D-glucose Chemical compound OC[C@@H](O)[C@@H](O)[C@H](O)[C@@H](O)C=O GZCGUPFRVQAUEE-SLPGGIOYSA-N 0.000 claims description 9
- 239000008187 granular material Substances 0.000 claims description 9
- 239000000945 filler Substances 0.000 claims description 6
- 238000009998 heat setting Methods 0.000 claims description 6
- 239000001913 cellulose Substances 0.000 claims description 5
- 229920002678 cellulose Polymers 0.000 claims description 5
- XSQUKJJJFZCRTK-UHFFFAOYSA-N Urea Chemical compound NC(N)=O XSQUKJJJFZCRTK-UHFFFAOYSA-N 0.000 claims description 4
- 239000004202 carbamide Substances 0.000 claims description 4
- ODGAOXROABLFNM-UHFFFAOYSA-N polynoxylin Chemical compound O=C.NC(N)=O ODGAOXROABLFNM-UHFFFAOYSA-N 0.000 claims description 2
- 238000001035 drying Methods 0.000 claims 1
- 230000003014 reinforcing effect Effects 0.000 claims 1
- 239000000463 material Substances 0.000 abstract description 12
- 238000000465 moulding Methods 0.000 abstract description 7
- 239000000758 substrate Substances 0.000 abstract description 2
- 239000000047 product Substances 0.000 description 4
- 238000012360 testing method Methods 0.000 description 4
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 3
- 229910000831 Steel Inorganic materials 0.000 description 3
- 239000003973 paint Substances 0.000 description 3
- 239000010959 steel Substances 0.000 description 3
- 235000002017 Zea mays subsp mays Nutrition 0.000 description 2
- 241000482268 Zea mays subsp. mays Species 0.000 description 2
- PNEYBMLMFCGWSK-UHFFFAOYSA-N aluminium oxide Inorganic materials [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 description 2
- TZCXTZWJZNENPQ-UHFFFAOYSA-L barium sulfate Chemical compound [Ba+2].[O-]S([O-])(=O)=O TZCXTZWJZNENPQ-UHFFFAOYSA-L 0.000 description 2
- 238000010438 heat treatment Methods 0.000 description 2
- 239000002904 solvent Substances 0.000 description 2
- 239000007858 starting material Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 239000003377 acid catalyst Substances 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 239000004411 aluminium Substances 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000003054 catalyst Substances 0.000 description 1
- 239000007795 chemical reaction product Substances 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
- 229910052570 clay Inorganic materials 0.000 description 1
- 239000002131 composite material Substances 0.000 description 1
- 239000000356 contaminant Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 235000013312 flour Nutrition 0.000 description 1
- 239000012530 fluid Substances 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 239000002075 main ingredient Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 239000011148 porous material Substances 0.000 description 1
- 239000011253 protective coating Substances 0.000 description 1
- 230000000717 retained effect Effects 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000005507 spraying Methods 0.000 description 1
- 239000003381 stabilizer Substances 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000454 talc Substances 0.000 description 1
- 229910052623 talc Inorganic materials 0.000 description 1
- 150000004684 trihydrates Chemical class 0.000 description 1
- 239000002023 wood Substances 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B24—GRINDING; POLISHING
- B24C—ABRASIVE OR RELATED BLASTING WITH PARTICULATE MATERIAL
- B24C11/00—Selection of abrasive materials or additives for abrasive blasts
Definitions
- This invention relates to a method of blast cleaning and a composition suitable for use therein.
- thermoset resin In the blast cleaning of surfaces, particularly those (eg of soft alloys or plastics composites) which might be damaged by the use of highly abrasive shot such as steel, it is known to employ high velocity particles comprising a thermoset resin. These particles may for example be suspended in a high-velocity stream of air or other gas or liquid such as water directed at the surface to be cleaned.
- cleaning we include not only the removal of dirt but also the stripping of paint or like protective coating.
- One procedure for making suitable abrasive particles is to take granules of an ordinary moulding composition, eg of cellulose-filled urea- formaldehyde resin, mould it conventionally under heat and mechanical pressure, ie with use of a moulding tool, comminute the heat-set moulded product, and sift the comminuted material into fractions of various particle sizes (eg BS mesh 10-20, 20-40 and 40-60) suited to particular surface-cleaning operations.
- an ordinary moulding composition eg of cellulose-filled urea- formaldehyde resin
- thermoset resin a urea formaldehyde resin having a molar ratio urea : formaldehyde in the range 1:1.2 to 1:1.6 and is heat-set without the application of mechanical pressure.
- the heat- setting operation referred to leads direct to a product that is utilisable in blast cleaning.
- Heat-setting which can be carried out in conventional steam-heated or electrically heated batch ovens, or in hot air driers such as fluid bed driers, with the resin in conventional granular form, need not be taken right to completion; materials of intermediate but still suitable hardness can be made by reducing the time for which the granules are held at curing temperature, eg to obtain a cure of only 90%.
- thermosetting resin employed is a urea-formaldehyde resin in which the molar ratio of urea : formaldehyde is in the range 1:1.2 to 1:1.6, preferably 1:1.3 to 1:1.5.
- the resin which is subjected to heat-setting without the application of mechanical pressure is in the form of granules, in which it is present either admixed with or absorbed in a filler such as cellulose, wood flour, alumina, alumina trihydrate, silica, talc, barium sulphate, clay or mixtures of these substances. Admixture or absorption affords a means of varying the abrasive properties of the end product.
- the granules can be made by first mixing the filler with a solution of the resin, driving off solvent from the mixture, and heating to a temperature at which the resin undergoes a degree of curing (up to about 50%) , sufficient to leave the mixture in a form known as "popcorn", capable of being fine-ground.
- the ground mixture is extruded hot eg 80°C and the extrudate is cut into granular form.
- solvent in limited amount eg water, in the case of a resin which is a formaldehyde condensate
- solvent in limited amount eg water, in the case of a resin which is a formaldehyde condensate
- the popcorn referred to earlier is used direct to make the abrasive particles, by further heating to increase the degree of cure of the resin in it without the application of mechanical pressure.
- the particles may be too friable for some applications.
- the particles are mixed with aqueous urea formaldehyde resin followed by heat setting the mixture in the absence of pressure to form a friable mass of resin reinforced particles.
- Such resin reinforced particles have proved to be more durable in the blast cleaning process. This is thought to be due to the aqueous resin at least partially filling the pores in the original heat set particles, thereby conferring improved strength/hardness.
- a free-flowing composition suitable for use in the method defined earlier consists essentially of abrasive particles which are predominantly in the size range BS 10 - 60, said particles comprising (a) resin reinforced granules of a urea formaldehyde resin which is heat-set without the application of mechanical pressure, and (b) a filler.
- the invention is further illustrated by the following Example.
- the starting material employed was a commercially available granular urea-formaldehydemoulding composition passing BS 8 mesh (2mm) and retained on BS 100 mesh (0.15mm), or which about 30% by weight was BS 10 - 20 mesh (1.7 - 0.8mm) and about 70% by weight was BS 20 - 60 mesh (0.8 - 0.25mm). Particles passing BS 60 mesh formed less than 5% by weight of the composition.
- the composition contained the usual small amounts of curing catalyst, stabiliser and mould lubricant.
- composition 25 kg was heated in an oven at 150°C for 1.5 hours, to bring the resin content from an initial 40 - 50% cure (too low to confer abrasiveness on the particles) to full cure.
- the cured product whose particle size distribution was substantially unchanged from that of the starting material, was separated into free-flowing BS 10 - 20 and BS 20 - 60 mesh fractions.
- a 25kg batch of commercially available, granular urea formaldehyde moulding material (UF ratio in the range 1:1.2 to 1:1.6) was mixed at room temperature with 10 litres of an aqueous urea formaldehyde resin of UF ratio 1:1.4 and 65% resin solids content.
- UF ratio in the range 1:1.2 to 1:1.6
- an acid catalyst was mixed in and the wet granular material was dried/heat-set (cured) on trays in an oven at 110°C for 16 hours.
- the product was a readily friable mass of resin reinforced particles. These were comminuted and sieved to give a particle size range of BS 10 - 60.
- Example 2 This material was compared with that of Example 1 by testing in a conventional air blast rig, using a test sample a steel panel coated with a standard automobile primer and top coat. The particles were sprayed through a nozzle of diameter 9.5mm using a spraying pressure of 240 kN/m 2 . The following results were achieved.
- the resin reinforced particles were thus significantly more effective than the unreinforced particles.
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Compositions Of Macromolecular Compounds (AREA)
- Detergent Compositions (AREA)
Abstract
In a method of blast cleaning a surface by exposing it to high-velocity abrasive particles comprising a thermoset resin, the resin employed is one that is heat-set without the application of mechanical pressure. No moulding operation is entailed during thermosetting of the resin; and there is during blast cleaning no danger of damage to the substrate such as may occur when comminuted (and often, contaminated) material from scrap mouldings is used.
Description
Blast cleaning method and composition
This invention relates to a method of blast cleaning and a composition suitable for use therein.
In the blast cleaning of surfaces, particularly those (eg of soft alloys or plastics composites) which might be damaged by the use of highly abrasive shot such as steel, it is known to employ high velocity particles comprising a thermoset resin. These particles may for example be suspended in a high-velocity stream of air or other gas or liquid such as water directed at the surface to be cleaned.
By "cleaning" we include not only the removal of dirt but also the stripping of paint or like protective coating. One procedure for making suitable abrasive particles is to take granules of an ordinary moulding composition, eg of cellulose-filled urea- formaldehyde resin, mould it conventionally under heat and mechanical pressure, ie with use of a moulding tool, comminute the heat-set moulded product, and sift the comminuted material into fractions of various particle sizes (eg BS mesh 10-20, 20-40 and 40-60) suited to particular surface-cleaning operations.
This, however, is a rather laborious route to a suitable composition; and a much simpler one is to use, as feedstock for comminution, the scrap that is available from commercial moulding establishments. The disadvantage of this latter approach is that the scrap may well be contaminated, as with inclusions of metal, and the presence of such contaminant material in a composition used for blast cleaning a surface could seriously harm the substrate.
According to the present invention, we provide a method of blast- cleaning a surface by exposing it to high-velocity abrasive particles comprising a thermoset resin, wherein the resin is a urea formaldehyde resin having a molar ratio urea : formaldehyde in the range 1:1.2 to 1:1.6 and is heat-set without the application of mechanical pressure.
Besides dispensing with the use of a moulding tool, the heat- setting operation referred to leads direct to a product that is utilisable in blast cleaning. Heat-setting, which can be carried out in conventional steam-heated or electrically heated batch ovens, or in hot air driers such as fluid bed driers, with the resin in conventional granular form, need not be taken right to completion; materials of intermediate but still suitable hardness can be made by reducing the time for which the granules are held at curing temperature, eg to obtain a cure of only 90%.
The thermosetting resin employed is a urea-formaldehyde resin in which the molar ratio of urea : formaldehyde is in the range
1:1.2 to 1:1.6, preferably 1:1.3 to 1:1.5.
-*
According to a preferred feature of the invention, the resin which is subjected to heat-setting without the application of mechanical pressure is in the form of granules, in which it is present either admixed with or absorbed in a filler such as cellulose, wood flour, alumina, alumina trihydrate, silica, talc, barium sulphate, clay or mixtures of these substances. Admixture or absorption affords a means of varying the abrasive properties of the end product. The granules can be made by first mixing the filler with a solution of the resin, driving off solvent from the mixture, and heating to a temperature at which the resin undergoes a degree of curing (up to about 50%) , sufficient to leave the mixture in a form known as "popcorn", capable of being fine-ground. The ground mixture is extruded hot eg 80°C and the extrudate is cut into granular form. Alternatively, solvent in limited amount (eg water, in the case of a resin which is a formaldehyde condensate) is added with stirring to the ground material, and the granules thus formed are then dried.
According to another feature of the invention, the popcorn referred to earlier is used direct to make the abrasive particles, by further heating to increase the degree of cure of the resin in it without the application of mechanical pressure.
Whilst the method just described gives satisfactory results, the particles may be too friable for some applications. According to a further preferred feature of the invention, the particles are
mixed with aqueous urea formaldehyde resin followed by heat setting the mixture in the absence of pressure to form a friable mass of resin reinforced particles. Such resin reinforced particles have proved to be more durable in the blast cleaning process. This is thought to be due to the aqueous resin at least partially filling the pores in the original heat set particles, thereby conferring improved strength/hardness.
According to another aspect of the invention, a free-flowing composition suitable for use in the method defined earlier consists essentially of abrasive particles which are predominantly in the size range BS 10 - 60, said particles comprising (a) resin reinforced granules of a urea formaldehyde resin which is heat-set without the application of mechanical pressure, and (b) a filler.
The invention is further illustrated by the following Example.
EXAMPLE 1
The starting material employed was a commercially available granular urea-formaldehydemoulding composition passing BS 8 mesh (2mm) and retained on BS 100 mesh (0.15mm), or which about 30% by weight was BS 10 - 20 mesh (1.7 - 0.8mm) and about 70% by weight was BS 20 - 60 mesh (0.8 - 0.25mm). Particles passing BS 60 mesh formed less than 5% by weight of the composition.
The main ingredients were (a) thermosetting resin of molar ration
urea : formaldehyde = 1:1.4, and (b) cellulose, in the weight proportion resin : cellulose = 70:30. The composition contained the usual small amounts of curing catalyst, stabiliser and mould lubricant.
The composition (25 kg) was heated in an oven at 150°C for 1.5 hours, to bring the resin content from an initial 40 - 50% cure (too low to confer abrasiveness on the particles) to full cure.
The cured product, whose particle size distribution was substantially unchanged from that of the starting material, was separated into free-flowing BS 10 - 20 and BS 20 - 60 mesh fractions.
These fractions were tested separately in a conventional air- blast cleaning rig using a nozzle pressure of 205 kN/m2 , to compare their ability to (i) strip a steel plate painted with standard undercoat and topcoat, and (ii) finish a standard aluminium panel. Results were as follows:
Test (i) Test (ii)
Area of paint Effect on removed/minute Al panel
Granular starting None Material impacted material on surface; no cleaning achieved
Cured material 270cm2 Uniform, fine BS 10 - 20 mesh finish
Cured material 230cm2 Uniform, fine BS 20 - 60 mesh finish
EXAMPLE 2
A 25kg batch of commercially available, granular urea formaldehyde moulding material (UF ratio in the range 1:1.2 to 1:1.6) was mixed at room temperature with 10 litres of an aqueous urea formaldehyde resin of UF ratio 1:1.4 and 65% resin solids content. At small amount of an acid catalyst was mixed in and the wet granular material was dried/heat-set (cured) on trays in an oven at 110°C for 16 hours. The product was a readily friable mass of resin reinforced particles. These were comminuted and sieved to give a particle size range of BS 10 - 60.
This material was compared with that of Example 1 by testing in a conventional air blast rig, using a test sample a steel panel
coated with a standard automobile primer and top coat. The particles were sprayed through a nozzle of diameter 9.5mm using a spraying pressure of 240 kN/m2. The following results were achieved.
Area of paint removed per
Blast Material Source minute
Example 1 116cm2
(Particle size BS 10 - 60)
Example 2 193cm2
(Particle size BS 10 - 60)
The resin reinforced particles were thus significantly more effective than the unreinforced particles.
Claims
1. A method of blast cleaning a surface by exposing it to high-velocity abrasive particles comprising a thermoset resin, characterised in that the resin is a urea- formaldehyde in the range 1:1.2 - 1:1.6 and is heat-set without the application of mechanical pressure.
2. A method according to claim 1, characterised in that the molar ratio urea : formaldehyde of the resin is in the range 1:1.3 - 1:1.5.
3. A method according to claim 1 or claim 2, characterised in that said particles are obtained by heat-setting the resin in a granular composition comprising thermosetting resin and filler.
4. A method according to any preceding claim characterised in that the heat set resin is mixed with aqueous urea formaldehyde resin followed by heat setting and drying the mixture in the absence of pressure to form a friable mass of resin reinforced granules.
5. A method according to claim 3 or claim 4 in which the filler is cellulose.
6. A free-flowing composition suitable for use in the method of claim 4 consisting essentially of abrasive particles which are predominantly in the size range BS 10 - 60, said particles comprising (a) resin reinforced granules of a urea-formaldehyde resin which is heat-set without the application of mechanical pressure, and (b) a filler.
7. A composition according to claim 6 characterised in that the reinforcing resin is a urea-formaldehyde resin.
8. A method of blast cleaning a surface using the composition of claim 6 or claim 7 suspended in a high velocity gas stream, the gas being preferably air.
9. A method of blast cleaning a surface substantially as described herein with reference to the Example.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB919123669A GB9123669D0 (en) | 1991-11-07 | 1991-11-07 | Blast cleaning method and composition |
| GB9123669.5 | 1991-11-07 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO1993008954A1 true WO1993008954A1 (en) | 1993-05-13 |
Family
ID=10704241
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/GB1992/002041 WO1993008954A1 (en) | 1991-11-07 | 1992-11-05 | Blast cleaning method and composition |
Country Status (2)
| Country | Link |
|---|---|
| GB (2) | GB9123669D0 (en) |
| WO (1) | WO1993008954A1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2143929C1 (en) * | 1993-04-30 | 2000-01-10 | Фармация энд Апджон АБ | Injection device for unlimited varied dosing and introduction of liquid preparation |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1997000157A1 (en) * | 1995-06-19 | 1997-01-03 | Sun Coast Holdings, Inc. | Process for making plastic blasting media from polyamine-aldehyde and polyphenol-aldehyde-containing materials |
| NL1007501C2 (en) * | 1997-11-10 | 1999-05-11 | Pieter Schurink | Cleaning surfaces by blasting to remove e.g. dirt, scale or paint |
| US6569214B2 (en) * | 2000-06-01 | 2003-05-27 | U.S. Technology Corporation | Composite polymer blast media |
| JP4053297B2 (en) * | 2001-04-11 | 2008-02-27 | 三菱マテリアル株式会社 | Grinding material and drilling method using the same |
| US6620215B2 (en) * | 2001-12-21 | 2003-09-16 | Dynea Canada, Ltd. | Abrasive composition containing organic particles for chemical mechanical planarization |
Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4545155A (en) * | 1982-08-20 | 1985-10-08 | Tokyo Shibaura Denki Kabushiki Kaisha | Method for removing flashes from molded resin product |
| US4731125A (en) * | 1984-04-19 | 1988-03-15 | Carr Lawrence S | Media blast paint removal system |
| FR2642335A1 (en) * | 1989-01-11 | 1990-08-03 | Thomann Bernard | Process for cleaning buildings and monuments with the aid of powder |
| WO1991005813A1 (en) * | 1989-10-20 | 1991-05-02 | Perstorp Ab | Process for the production of a white fine-grained material of urea-formaldehyde resin or a modified urea-formaldehyde resin |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| AU586765B2 (en) * | 1986-09-24 | 1989-07-20 | Foseco International Limited | Abrasive media |
-
1991
- 1991-11-07 GB GB919123669A patent/GB9123669D0/en active Pending
-
1992
- 1992-11-04 GB GB9223055A patent/GB2261182B/en not_active Expired - Fee Related
- 1992-11-05 WO PCT/GB1992/002041 patent/WO1993008954A1/en active Application Filing
Patent Citations (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4545155A (en) * | 1982-08-20 | 1985-10-08 | Tokyo Shibaura Denki Kabushiki Kaisha | Method for removing flashes from molded resin product |
| US4731125A (en) * | 1984-04-19 | 1988-03-15 | Carr Lawrence S | Media blast paint removal system |
| FR2642335A1 (en) * | 1989-01-11 | 1990-08-03 | Thomann Bernard | Process for cleaning buildings and monuments with the aid of powder |
| WO1991005813A1 (en) * | 1989-10-20 | 1991-05-02 | Perstorp Ab | Process for the production of a white fine-grained material of urea-formaldehyde resin or a modified urea-formaldehyde resin |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| RU2143929C1 (en) * | 1993-04-30 | 2000-01-10 | Фармация энд Апджон АБ | Injection device for unlimited varied dosing and introduction of liquid preparation |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2261182B (en) | 1995-03-22 |
| GB9123669D0 (en) | 1992-01-02 |
| GB2261182A (en) | 1993-05-12 |
| GB9223055D0 (en) | 1992-12-16 |
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