HK1140468B - Method of producing aqueous suspensions of calcium carbonate and suspensions obtained, as well as the uses thereof - Google Patents

Description

The present invention relates to mineral materials obtained by wet milling, possibly dried, for use in the paper, paint, plastic and plaster industry and more particularly to a process for the manufacture of aqueous suspensions by wet milling of calcium carbonate to obtain an aqueous suspension of calcium carbonate used in the paper industry.

Natural calcium carbonate (CCC) is a mineral pigment commonly used in coating sauces to cover paper and give it optical properties such as opacity. This calcium carbonate is initially produced as an aqueous suspension, which is easier to transport, handle and transfer than a dry powder.

One method of manufacturing such a suspension is to grind the calcium carbonate in question in water in the presence of a grinding aid agent until a certain particle size is obtained, i.e. a certain particle size distribution. During this step, a so-called grinding aid agent is used, the function of which is to facilitate the mechanical action of grinding. It is generally a homopolymer or copolymer of acrylic acid obtained by conventional polymerisation processes in emulsion or solution (see in particular Documents FR 2 539 137, FR 2 683 536, FR 2 683 537, FR 2 688, FR 2683 539, FR 2 533 532, FR 2 683 533).

Secondly, the dry extract of this suspension is increased, i.e. the amount by dry weight of calcium carbonate is increased in relation to the total weight of the suspension by water removal, thus producing the finest possible mineral-rich end product.

It is important to have an aqueous suspension of mineral material which remains sufficiently fluid over time. This property can be understood very simply by measuring viscosities of the suspension at BrookfieldTM immediately after grinding and then 8 days afterwards, without agitating the medium.

Another constraint, incorporated by the present invention, is to obtain a suspension of calcium carbonate leading to the highest possible opacity of the coated sheet of paper. It has long been known that opacity is related to a certain distribution of the sizes of individual calcium carbonate particles within the aqueous suspension. This distribution must be as narrow as possible; it is also called a granulometer distribution vertical , in view of the shape of the obtained curve (percentage by weight of particles having a given diameter in function of diameter).

The verticalness or narrowness of the particle size distribution is reflected by the slope factor, a well-known parameter for the professional, calculated as the ratio of the percentage by weight of particles with a diameter of less than one diameter d1 to the percentage by weight of particles with a diameter of less than another diameter d2, i.e.: The higher the slope factor, the more narrow the particle size distribution and the better the opacity of the final coated paper. This idea is supported in particular in the paper Pigment concepts for improved paper and print properties (P. Burri, ATIP Conference, June 23, 2000 Tour), especially on page 4.

Thus, EP 0 894 836 describes an aqueous suspension of GCC, one of the characteristics of which is a slope factor (d50/d20) between 1.5 and 2, preferably between 1.5 and 1.75.

Similarly, WO 2007 / 031870 describing co-grinding of precipitated calcium carbonate or PCC with a CCC in aqueous medium, allows co-grinding of a pigment with a slope factor of 100 x (d30/d70) greater than 30, preferably 40, very preferably 45, and increases the opacity of the final paper (see Table 2).

In the same sense, the professional is also familiar with documents EP 0 850 685, WO 00/39029 and EP 0 894 833, which describe a process in which the preparation step of the aqueous suspension is carried out in such a way as to result in a solid content not exceeding 40%, or with document EP 0 607 840, which describes a process in which the concentration in solid matter is less than or equal to 24%.

In parallel, another option to this need to first grind calcium carbonate to obtain a high slope factor is that the tradesman seeks to maximize the final dry extract through the second step of water removal which is particularly energy-intensive.

Continuing his research to offer the professional a solution which allows: to obtain a higher slope factor than with the grinding aids of the previous technology, and thus an improved or at least equal opacity,while grinding initially at the same concentration,and removing water to the same final dry extract,to have a final aqueous suspension stable over time, The applicant has developed a process for the manufacture of an aqueous suspension of natural calcium carbonate characterised by the following steps: (a) dry and/or wet pre-crushing of calcium carbonate to an average diameter of 0,(b) form an aqueous suspension of the product obtained from step (a) by adding the necessary amount of water to obtain a dry calcium carbonate content of between 10% and 80%, preferably between 30% and 50% and very preferably between 35% and 45%;(d) where appropriate, concentrate the aqueous suspension obtained at step (c) by any known means to obtain a calcium carbonate content of at least 5% above the concentration in step (b) or (c), preferably between 60% and 80% by weight, very preferably between 65% and 75% by weight, (e) add possibly a dispersant to the aqueous suspension during or after step (d),(f) the product obtained by step (c) or (d) or (e) may be dried by any known means.

It is noted that throughout this Application, molecular weights, as well as molar contents in polymer chains with a molecular weight below a certain value, are determined by a special method as described in the introduction of the examples.

Therefore, and surprisingly, compared with an earlier technique using a conventional grinding aid, i.e. a homopolymer and/or copolymer of acrylic acid (meth) not meeting the two previous conditions, the homopolymers and copolymers of acrylic acid (meth) used in the process of the invention allow: The method of extraction is based on the following principles: the first is to use the same dry extract as in the previous method, to obtain a higher slope factor of 100 * (d25 / d75) and thus a better opacity (S), while also producing water suspensions that are stable over time.

In practice, the professional has for many years identified a parameter which, measured at the level of the calcium carbonate suspension, moves in the same direction as the opacity of the coated sheet: this is the coefficient of light scattering of the suspension (S expressed in m2/kg) when applied to a support.

Thus, one of the applicant's merits is that it was able to identify that the choice of a particular range of molecular weights, in combination with a limited fraction of low molecular weight polymer chains, was the optimal combination to obtain an aqueous suspension that was both stable and had a high slope factor, which meant an improved opacity of the coated sheet.

In addition, it is easy for the professional to manufacture polymers with this combination of characteristics, particularly from the so-called separation techniques and controlled radical polymerization methods such as the so-called RAFT technique (reversible transfer by addition fragmentation).

The first are relatively old methods (early 1980s), and aim at purifying the polymer as obtained after its synthesis.They implement steps to isolate populations of polymer molecular chains with a given molecular weight (through a choice of solvents and appropriate temperatures) and lead to a given molecular weight on the one hand, and to the content chosen for polymer chains, for example, with a molecular weight below a certain limit.

The second are manufacturing techniques that allow, in particular by the implementation of special catalysts, to control the distribution of molecular weights during the polymerization reaction. The choice of synthesis conditions (such as the catalyst/monomer ratio used) allows the professional to achieve both a given molecular weight and a content of polymer chains whose molecular weight is less than a certain one. The professional can refer in particular to documents WO 02 / 070571, WO 2004 / 014967 and WO 2005 / 095466, as well as to publications Dispersion of calcite by polycytes (sodium acrylate) Refractory polymerization by polymerization (polymerization) Refractory polymerization by polycytes (Macra), Refractory polymerization by polycytes (Macra), Refractory polymerization by polycytes (Macra), Refractory polymerization by polycytes (Macra), Refractory polymerization by polycytes (Macra), Refractory polymerization by polycytes (Macra), Refractory polymerization by polycytes (Macra), Refractory polymerization by polycyl) Refractory polymerization by polycyl (Macra), Refractory polymerization by polycyl (Macra), Refractory polymerization by Chrom (Macra), Refractory Polymerization by Chrom (RRR), Refractory Chrom), Refractory Chrom (RRRractory Chrom), , 2003), Refractory Chrom (RRRRRRRRRRRRRRRRRRRRRRR), RRRRRRRRRRRRRRRRR), RRRRRRRRRRRRRRRRRRRRRR,RRRRRRRRRRRRRRRRRR,RRRRRRRR

It is also important to note that none of the above papers concerning controlled radical separation and polymerization methods specifically refer to a process for manufacturing calcium carbonate by grinding and then concentration in aqueous media. It should be noted here that this is a very particular process, as presented in WO 02/49765, where an acrylic polymer with very specific neutralization rates in mono- and divalent cations leads to an aqueous suspension with a small amount of unsorbed grinding agent on the surface of the calcium carbonate.

The first object of the invention is therefore a process for the manufacture of an aqueous suspension of natural calcium carbonate characterized by the following steps: (a) by adding the necessary quantity of water to obtain a dry calcium carbonate content of between 10% and 80%, preferably between 30% and 50% and very preferably between 35% and 45%; (c) by grinding the suspension obtained from step (b) in the presence of a homopolymer and/or copolymer of acrylic acid (meth) having a molecular weight of between 8 000 g/mol and 15 000 g/mol at the same time;preferably between 10 000 g/mol and 14 000 g/mol, very preferably in the order of 12 000 g/mol and a molar content in polymer chains of less than 3 000 g/mol by molecular weight less than 20%, preferably 15%, very preferably 10%, to obtain a calcium carbonate content of at least 5% above the concentration in step (b) or (c), preferably between 60% and 80% by weight, very preferably between 65% and 75% by weight,(e) add possibly a dispersant to the aqueous suspension during or after step (d);

In a first variant, this process is also characterised by the homopolymer and/or copolymer of acrylic acid (meth) being obtained by radical polymerisation in emulsion or solution, followed by at least one static or dynamic separation step, which involves one or more polar solvents, preferably belonging to the group consisting of water, methanol, ethanol, propanol, isopropanol, butanols, acetone, tetrahydrofuran or mixtures thereof.

In a second variant, this process is also characterised by the homopolymer and/or copolymer of acrylic acid (meth) being obtained by controlled radical polymerisation, preferably by reversible transfer polymerisation by addition fragmentation (RAFT).

It is important to emphasize that the skilled person has, on the basis of his knowledge and the state of the art, all the necessary elements to manufacture a polymer which verifies the dual characteristic which is the subject of this Application: in this sense, it is his own to synthesize the polymers which are the subject of this invention.

In this second variant, this use is also characterised by the fact that the reverse transfer polymerisation by addition fragmentation (RAFT) employs at least one chain transfer agent, as claimed in WO 02 / 070571, WO 2004 / 014967 and WO 2005 / 095466,

In general, this process is also characterised by the homopolymer and/or copolymer of acrylic acid (meth) being either totally acidic, or totally or partially neutralized by a neutralizing agent chosen from sodium, potassium, calcium, magnesium, ammonia hydroxides and/or oxides, or mixtures thereof, preferably by a neutralizing agent chosen from sodium hydroxide, potassium, ammonia, or mixtures thereof, very preferably by a neutralizing agent which is sodium hydroxide.

In general, this process is characterised by the fact that, in addition to acrylic acid (meth), the said copolymer of acrylic acid (meth) contains another monomer selected from acrylic anhydride (meth), acrylamide (meth), acrylic esters (meth) and preferably from acrylates of methyl, ethyl, isopropyl, n-propyl, isobutyl, n-butyl, ter-butyl, 2-ethylhexyl, methyl methacrylates, methyl methacrylates, methyl methacrylates, hydroxylated methacrylates, styrene, methyl methacrylate, styrene, or acrylamide, especially methyl methacrylate, isopropyl-2-methyl and their precursors, such as sulphuryl methacrylate, methyl methacrylate, styrene, styrene, acrylamide, and their sulphate and sulphuryl methacrylate.

This process is also characterised by the fact that the homopolymer and/or copolymer of acrylic acid (meth) is used at a rate of 0.1 to 1.0%, preferably 0.2 to 0.6% by dry weight, compared with calcium carbonate by dry weight.

This process is also characterised by the fact that, in addition to the homopolymer and/or copolymer of acrylic acid (meth), another homopolymer and/or copolymer of acrylic acid (meth) is used together during the concentration step (d).

This process is also characterised by the fact that the concentration of calcium carbonate in the aqueous suspension obtained at the end of the grinding step (c) is between 10% and 80% by dry weight of the total weight of the suspension, preferably between 30% and 50%, very preferably between 35% and 45%.

In one variant, this process is also characterised by the concentration of calcium carbonate in the aqueous suspension at the dry weight of the concentration step (d) being at least 5% above the concentration of the product in step (b) or (c), preferably between 60% and 80%, and very preferably between 65% and 75%.

Another subject matter of the invention is the aqueous suspension of calcium carbonate containing the homo- or copolymer and its use in the paper, paint, plastics and mastics industries and in particular its use in paper applications such as bulk loading or coating.

The invention also relates to the coating sauce or bulk filling composition containing the aqueous suspension of calcium carbonate.

Examples The Commission shall adopt the implementing acts referred to in paragraph 1.

Throughout this Application, the granulometer characteristics of calcium carbonate are determined from a SedigraphTM 5100 apparatus marketed by MICROMERITICSTM.

The light scattering factor S is determined according to the method given in FR 2 885 906.

Molecular weights, the molar contents of polymer chains with a molecular weight below a given value, are determined by the following method.

A test sample of the polymer solution corresponding to 90 mg of dry matter is introduced into a 10 ml vial. The mobile phase, with 0.04% DMF added, is added to a total mass of 10 g. The composition of this mobile phase is as follows: NaHCO3 : 0.05 mol/L, NaNO3 : 0.1 mol/L, triethanolamine: 0.02 mol/L, NaN3 0.03% by mass. The CES chain consists of an isocratic pump of type WatersTM 510 with a flow rate of 0.8 mL/min, a Waters 717+ sampling device, an oven containing a pre-column of type Guard Column Ultrahydrogel WatersTM ,followed by a linear column of type Ultrahydrogel Waters TM 30 cm long and 7,8 mm inside diameter. The detection is carried out by a WatersTM 410 differential refractometer. The CES is calibrated with a series of sodium polyacrylate standards supplied by Polymer Standard Service with a peak molecular weight between 2000 and 1.106 g/mol and a polymorphism index between 1.4 and 1.7, and with a sodium polyacrylate with a molecular weight of 5 600 g/mol and a polymorphism index of 2,4. The calibration curve is linear and takes into account the correction obtained by the flow marker (FDM). The chromatogram is acquired and processed by using the WinGPC Scientific v 4.0 PSS software. The resulting chromatogram is embedded in the area corresponding to molecular weights greater than 65 g/mol.

Example 1

This example illustrates a process for manufacturing calcium carbonate by grinding and then concentrating, depending on the invention or the present state of the art, using the same dispersant polymer during the concentration step. It illustrates the influence of the polymers used during the grinding step on the stability of the final suspensions (measurement of certain BrookfieldTM viscosities at different times), as well as on the particle size distribution - slope factor f = 100 x (d25 / d75) - and on the light scattering coefficient (S).

For each of the tests Nos 1 to 10, an aqueous suspension of calcium carbonate is formed for grinding in water, according to methods well known to the professional (see the grinding protocol as described in WO 02 / 49765). This calcium carbonate is a dry pre-crushed Carrara marble to a median diameter of approximately 10 μm. This milling step is intended to obtain a dry weight content of calcium carbonate equal to 50% of the total weight of the suspension. It is carried out in the presence of 0,45% by dry weight of a polymer according to tests Nos 1 to 10 in relation to the total dry weight of calcium carbonate.

In a further step, the suspension is concentrated using a laboratory thermal evaporator of the EPCONTM brand until a dry weight concentration of calcium carbonate of 71% of the total weight of the suspension is obtained. This concentration step is carried out in the presence of 0.25% by dry weight of calcium carbonate by dry weight, a mixture (70/30 dry weight ratio) of acrylic acid homopolymer, with a molecular weight of 10 400 g/mol, of which 100% by moles of carboxylic acids are neutralized by the solder, and phosphoric acid.

The first test

This test illustrates the previous state of the art and uses an acrylic acid homopolymer (according to WO 02/49765) obtained by conventional radical polymerization without separation, of which 50% by mole of the carboxylic sites are neutralized by sodium, 15% by calcium and 15% by magnesium, with a molecular weight of 9 600 g/mol, and of which 25% by mole of the polymer chains have a molecular weight of less than 3 000 g/mol.

Test number two

This test illustrates the previous state of the art and uses an acrylic acid homopolymer obtained by conventional radical polymerization without separation, totally neutralized by soda, with a molecular weight of 3 100 g/mol, of which 65% by mole of the polymer chains have a molecular weight of less than 3 000 g/mol.

The third test

This test illustrates the previous state of the art and uses an acrylic acid homopolymer obtained by conventional radical polymerization followed by a separation, totally neutralized by soda, with a molecular weight of 5 500 g/mol, of which 37% by mole of the polymer chains have a molecular weight of less than 3 000 g/mol.

The fourth test

This test illustrates the previous state of the art and uses an acrylic acid homopolymer obtained by conventional radical polymerization without separation, totally neutralized by soda, with a molecular weight of 5 700 g/mol, and of which 40% by mole of the polymer chains have a molecular weight of less than 3 000 g/mol.

The first is the

This test illustrates the previous state of the art and uses a homopolymer of acrylic acid obtained by RAFT, totally neutralized by soda, with a molecular weight of 8 150 g/mol, of which 24% in mole of the polymer chains have a molecular weight of less than 3 000 g/mol.

The first is the

This test illustrates the previous state of the art and uses an acrylic acid homopolymer obtained by conventional radical polymerization without separation, totally neutralized by soda, with a molecular weight of 9 400 g/mol, of which 27% by mole of the polymer chains have a molecular weight of less than 3 000 g/mol.

The first is the

This test illustrates the previous state of the art and uses an acrylic acid homopolymer obtained by conventional radical polymerization without separation, totally neutralized by soda, with a molecular weight of 33 100 g/mol, of which 17% by mole of the polymer chains have a molecular weight of less than 3 000 g/mol.

The first is the

This test illustrates the previous state of the art and uses a homopolymer of acrylic acid obtained by RAFT, totally neutralized by soda, with a molecular weight of 31 000 g/mol, of which 12% in moles of the polymer chains have a molecular weight of less than 3 000 g/mol.

The first is the

This test illustrates the invention and implements an acrylic acid homopolymer obtained by conventional radical polymerization followed by a separation, totally neutralized by soda, of a molecular weight of 11 500 g/mol, of which 17% by mole of the polymer chains have a molecular weight of less than 3 000 g/mol.

The first is the

This test illustrates the invention and implements a homopolymer of acrylic acid obtained by RAFT, totally neutralized by soda, with a molecular weight of 10 800 g/mol, of which 18% by mole of the polymer chains have a molecular weight of less than 3 000 g/mol. The characteristics of the polymers used during the grinding stage are shown in Table 1, the values of the dry extracts after grinding stage (c) and concentration stage (d) (noted ESc and ESd respectively) and the percentage by weight of particles with diameters less than 1 μm and 2 μm (noted % < 1 μm and % < 2 μm respectively) are shown. - What?

The measurements could not be made for tests No 7 and 8 because the polymers were too heavy to be crushed to a dry extract of close to 50%.

In the second stage, for tests Nos 1 to 6, 9 and 10, the stability of the suspensions obtained was determined by measuring their BrookfieldTM viscosity at t=0 and t=8 days (without prior agitation, at 25°C and 10 rpm) at μ0 and μ8 (mPa.s.) respectively. - What?

It is noted that the viscosities obtained for tests Nos 1, 2, 5 and 6 are well above 5 000 mPa.s after 8 days; the corresponding aqueous suspension is therefore difficult to manipulate and particularly difficult to pump.

Finally, for suspensions where grinding has been possible and for which the viscosity of the BrookfieldTM (at 25°C and 10 RPM, 8 days before agitation) is less than 5 000 mPa.s, the slope factor f = 100 * (d25 / d75) and the light scattering coefficient S were determined.

	5 500	5 700	11 500	10 800
	37	40	17	18
	31,0	30,4	32,3	34,0
	136	138	141	144

Table 3 clearly shows that only tests Nos. 9 and 10 corresponding to the invention lead to a marked improvement in slope factor and opacity. In summary, only acrylic acid homopolymers obtained by RAFT or separation techniques, which have the dual characteristic of having a molecular weight between 8 000 g/mol and 15 000 g/mol on the one hand and a molar content of polymer chains with a molecular weight below 3 000 g/mol, allow: The results of the analysis were that the calcium carbonate was crushed under the conditions of the sample to obtain suspensions with rheological behaviour after 8 days in accordance with the requirements of the craftsman and with improved slope factor and light scattering coefficient S.

Claims (17)

1. Method of making an aqueous suspension of natural calcium carbonate characterized in that it comprises the following steps:

   a) dry and/or wet pre-grinding of calcium carbonate to an average diameter of 0.5 to 500 microns (d₅₀) in the presence or absence of dispersing agents,

   b) forming an aqueous suspension of the product from step a) by adding the necessary amount of water to obtain a dry calcium carbonate content of between 10% and 80%, preferably between 30% and 50% and more preferably between 35% and 45%,

   c) grinding the suspension from step b) in the presence of a homopolymer and/or copolymer of (meth)acrylic acid simultaneously having a molecular weight between 8000 g/mol and 15000 g/mol, preferably between 10000 g/mol and 14000 g/mol, more preferably of 12000 g/mol and a molar content of polymer chains of molecular weight of less than 3000 g/mol less than 20%, preferably 15%, more preferably 10%,

   d) optionally concentrating the aqueous suspension obtained in step c) by any known means to obtain a calcium carbonate content of at least 5% above the concentration of step b) or c), preferably between 60 and 80 wt.%, and more preferably between 65 and 75 wt.%,

   e) optionally adding a dispersing agent to the aqueous suspension during or after step d).
2. Method according to claim 1, characterized in that said homopolymer and/or copolymer of (meth)acrylic acid is obtained by emulsion or solution free radical polymerization, followed by at least one step of static or dynamic separation, wherein said separation step uses one or more polar solvents, preferably selected from the group consisting of water, methanol, ethanol, propanol, isopropanol, butanols, acetone, tetrahydrofuran or mixtures thereof.
3. Method according to claim 1, characterized in that said homopolymer and/or copolymer of (meth)acrylic acid is obtained by controlled free radical polymerization, preferably by reversible addition-fragmentation chain transfer (RAFT) polymerization.
4. Method according to claim 3, characterized in that the reversible addition-fragmentation chain transfer (RAFT) polymerization uses at least one chain transfer agent, such as claimed in WO 02/070571, WO 2004/014967 and WO 2005/095466.
5. Method according to any one of claims 1 to 4, characterized in that said homopolymer and/or copolymer of (meth)acrylic acid is totally acid, or totally or partially neutralized by a neutralizing agent selected from sodium and potassium hydroxides, calcium and magnesium hydroxides and/or oxides, ammonia, or mixtures thereof, preferably by a neutralizing agent selected from sodium hydroxide, potassium hydroxide, ammonia, or mixtures thereof, more preferably by a neutralizing agent which is sodium hydroxide.
6. Method according to any one of claims 1 to 5, characterized in that, in addition to (meth)acrylic acid, said copolymer of (meth)acrylic acid contains another monomer selected from (meth)acrylic anhydride, (meth)acrylamide, (meth)acrylic esters and preferably from methyl, ethyl, isopropyl, n-propyl, isobutyl, n-butyl, tert-butyl, 2-ethylhexyl acrylates, methyl, ethyl methacrylates, hydroxy methacrylates, styrene, alpha-methylstyrene, styrene sulfonate, or acrylamido-2-methyl-2-propanesulfonic acid, acrylate phosphates and ethylene glycol methacrylate, and mixtures thereof, and in that the said other monomer is preferably acrylamide.
7. Method according to any one of claims 1 to 6, characterized in that said homopolymer and/or copolymer of (meth)acrylic acid is used in an amount of 0.1 to 1.0%, preferably of 0.2 to 0.6 dry wt.%, based on the dry weight of calcium carbonate.
8. Method according to any one of claims 1 to 7, characterized in that, in addition to said homopolymer and/or copolymer of (meth)acrylic acid, another homopolymer and/or copolymer of (meth)acrylic acid is used during or after the concentration step d).
9. Method according to any one of claims 1 to 8, characterized in that the calcium carbonate dry weight concentration of the aqueous suspension obtained after grinding step c) is between 10% and 80% of the total weight of said suspension, preferably between 30% and 50%, more preferably between 35% and 45%.
10. Method according to any one of claims 1 to 9, characterized in that the calcium carbonate dry weight concentration of the aqueous suspension obtained after the optional concentration step d) is at least 5% above the product concentration from step b) or c), is preferably between 60% and 80%, more preferably between 65% and 75% of the total weight of said suspension.
11. Method according to any one of claims 1 to 10, characterized in that it further comprises a drying step f) of drying, by any known means, the product obtained in step c) or d) or e) to produce a dry calcium carbonate.
12. Dry calcium carbonate characterized in that it is obtained according to the method of claim 11.
13. Aqueous suspension of calcium carbonate characterized in that it contains a homopolymer and/or copolymer of (meth)acrylic acid used in the method according to any one of claims 1 to 11.
14. Use of the aqueous suspension of calcium carbonate according to claim 13 in paper applications such as filling or coating.
15. Coating formulation containing the aqueous suspension of calcium carbonate according to claim 13.
16. Filling composition containing the aqueous suspension of calcium carbonate according to claim 13.
17. Use of the aqueous suspension of calcium carbonate according to claim 13 in the paint, plastic and sealant industry.