JPH0726015A - Production of polyamide resin - Google Patents

Abstract

PURPOSE:To produce a polyamide resin with a high heat distortion temp. by producing a precondensate with a specified relative viscosity, continuously crushing it during its derivery from a polymerizer, and increasing the degree of polymn. of the crushed precondensate. CONSTITUTION:A dicarboxylic acid component (e.g. terephthalic or adipic acid) and an aq. soln. of a diamine (e.g. hexamethylenediamine) are fed into a pressurized polymerizer and reacted at 150-350 deg.C under a pressure of 2-70kg/cm<2>G to give a precondensate with a relative viscosity (in sulfuric acid, in a concn. of 1%, at 25 deg.C) of 1.04-2.5. The precondensate is crushed to a granule size of 0. 2-10mm and caused to dwell in a melting machine at a temp. 10-70 deg.C higher than the m.p. of the precondensate but not higher than 370 deg.C for 20min or longer to increase the degree of polymn., giving a polyamide resin having a relative viscosity of 1.8-5.0 and comprising structural units of formulas I, II, III, and IV in wt. ratios of (I/II), (I/III), and (I/IV) of (55/45)(80/20), (20/80)-(80/20), and (55/45)-(90/10), respectively.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a polyamide resin, and more particularly to a method for producing a heat-resistant polyamide resin suitable for automobile parts and electric / electronic parts.

[0002]

2. Description of the Related Art Polyamides have been widely used in the fields of automobiles, electric and electronic fields, etc. by utilizing their excellent properties as engineering plastics. Conventionally, these molded products have been made of glass fiber reinforced nylon 6 and nylon 66 (Japanese Patent Laid-Open No. 59-161461).
With the recent rise in the temperature of the engine room of automobiles and the progress of microelectronics due to technological innovations, there has been a demand for materials for molded products that can withstand use in higher temperature atmospheres. However, the melting points (Tm) of nylon 6 and nylon 66 are 220 ° C and 260 ° C, respectively.
Therefore, even when reinforced with glass fiber, the limit of the heat distortion temperature is only the melting point.

Recently, many copolyamide resins having terephthalic acid and isophthalic acid components or their glass-reinforced products have been proposed as copolyamide resins capable of withstanding use under these high temperature atmospheres (JP-A-59-59).
161428, JP-A-59-155426, JP-A-59-53536, and JP-A-62-15.
No. 6130). In addition, as a method for producing these, a method of performing a polymerization reaction in a solid state from a nylon salt to a polymer has been proposed (JP-A-62-20527).
Issue).

[0004]

However, the copolyamide resin having these terephthalic acid and isophthalic acid components has a high melt viscosity as the number of terephthalic acid component units increases, and it is impossible to discharge the polymer by a usual melt polymerization method. Since the melting point was close to the thermal decomposition temperature of the polymer, it was decomposed or deteriorated during melt polymerization. Further, the method of carrying out the polymerization reaction in a solid state from the nylon salt to the polymer has a problem that the composition of the polymer is not stable.

[0005]

In view of the above situation, the present inventors have proposed a method for stably producing an inexpensive polyamide resin having a high rigidity and a high heat distortion temperature that can sufficiently withstand use in a high temperature atmosphere. As a result of diligently studying, the primary condensate is polymerized, the primary condensate is discharged from the polymerization tank, continuously pulverized, and then efficiently increased by increasing the degree of polymerization,
The present invention has been accomplished by finding that a stable polymer having a high degree of polymerization can be obtained. That is, the present invention is a hexamethylene terephthalamide unit represented by the following structural formula (I),

[0006] And any unit selected from the following structural formulas (II) to (IV)

[0007]

[0008]

[0009] And the copolymerization ratio is (I) / (II) = 55 by weight.
/ 45-80 / 20 or (I) / (III) = 20/80
~ 80/20 or (I) / (IV) = 55 / 45-90
In producing a polyamide resin in the range of / 10,
Under conditions of 150 to 350 ° C., a primary condensate having a relative viscosity (η _r ) at 25 ° C. of a 1% sulfuric acid solution of 1.04 to 2.5 is polymerized, and the primary condensate is discharged from a polymerization tank to continuously It is a method for producing a polyamide resin, which comprises pulverizing the primary condensate and then increasing the degree of polymerization of the primary condensate.

In the present invention, the polyamide resin is any one selected from hexamethylene terephthalamide unit (I), hexamethylene isophthalamide unit (II), hexamethylene adipamide unit (III) and caproamide unit (IV). A copolymerized polyamide formed from these units and having a (I) / (II) copolymerization ratio of 5 by weight.
5/45 to 80/20 (hereinafter, referred to as 6T / 6I copolyamide) or (I) / (III) copolymerization ratio is 20/80 to 80/20 in weight ratio (hereinafter, referred to as 6T / 66 copolyamide) Alternatively, the copolymerization ratio of (I) / (IV) is 55/45 to 90/10 (hereinafter referred to as 6T / 6 copolyamide) in weight ratio.

In the case of 6T / 6I, the polyamide resin of the present invention must have a copolymerization ratio of 55/45 to 80/20 by weight, preferably 60/40 to 80 /.
20, more preferably 60/40 to 70/30.
In the case of 6T / 66, the copolymerization ratio is 20/80.
To 80/20, preferably 25/75 to 70/3
0, more preferably 25/75 to 60/40. In the case of 6T / 6, the copolymerization ratio is 55/45.
To 90/10, preferably 60/40 to 85/1
5, more preferably 60/40 to 80/20. Here, the hexamethylene terephthalamide unit copolymerization ratio of 6T / 6I, 6T / 66, 6T / 6 copolyamide is 40/60, 20/80, 55/45, respectively.
If it is less than the above range, the melting point of the polymer is lowered, and the heat resistance such as the heat distortion temperature is lowered, which is not preferable. Also, 6
The hexamethylene terephthalamide unit copolymerization ratios of T / 6I, 6T / 66 and 6T / 6 are 80/2, respectively.
When it is more than 0, 80/20, 90/10, the melting point of the polymer becomes high and the heat resistance is improved, but the processing temperature becomes high and the polymer is thermally decomposed, which is not preferable.

The primary condensate of the present invention is prepared by charging an aqueous monomer raw material solution into a pressure type polymerization tank and stirring the mixture at 150 to 350 ° C.
It is obtained by heating to. In order to increase the efficiency of the polymerization tank, the raw material form is 50% or more of the raw material mixed aqueous solution,
It is preferable to concentrate the mixture to 65% or more.
The reaction temperature must be 150 to 350 ° C, preferably 180 to 340 ° C, more preferably 190 to 340 ° C.
℃. When the reaction temperature is lower than 150 ° C, the reaction time becomes long, which is not preferable. Further, if the reaction temperature is higher than 350 ° C., foaming or gel-like foreign matter is significantly generated due to thermal decomposition of the primary condensate, which is not preferable.

The pressure for producing the primary condensate of the present invention is usually 0 to 100 kg / cm ² -G, preferably ^{2 to} 70 kg.
/ Cm ² -G, more preferably 5 to 60 kg / cm ² -G. Since the primary condensate gives a remarkable freezing point depression due to the presence of a small amount of water, it can be discharged from the polymerization tank in a molten state at a temperature of 150 to 350 ° C.
The relative viscosity (η _r ) of the 1% sulfuric acid solution of the primary condensate of the present invention at 25 ° C. needs to be 1.04 to 2.5, preferably 1.08 to 2.3, and more preferably It is in the range of 1.08 to 2.1. When the relative viscosity is less than 1.04, the reaction time in the subsequent high polymerization degree step becomes long, and when the relative viscosity is more than 2.5, the melt viscosity of the primary condensate becomes too high and ejection failure occurs. Not preferable.

Further, in the usual polyamide polymerization, it is common to charge the raw materials so that the total amount of COOH groups and the total amount of NH ₂ groups contained in the monomer and the salt are equal to each other. A primary condensate having a large number of COOH groups or NH ₂ groups can be prepared by adding a dicarboxylic acid component or a diamine component at the time of charging the raw materials. A preferable charging ratio is to charge the dicarboxylic acid component or the diamine component in an excess of 0 to 10 mol% with respect to the total number of moles of the constituent monomers. If it exceeds 10 mol%, it is difficult to increase the degree of polymerization, which is not preferable. The dicarboxylic acid component is not particularly limited, and examples thereof include aliphatic dicarboxylic acid components such as adipic acid and sebacic acid, and aromatic dicarboxylic acids such as terephthalic acid isophthalic acid. The diamine component is not particularly limited,
For example, an aliphatic diamine such as tetramethylenediamine and hexamethylenediamine can be used. When the dicarboxylic acid component or diamine component is overcharged, a shortage of the diamine component or dicarboxylic acid component can be added in order to control the polymerization rate in the melt polymerization degree increasing step.

Furthermore, in order to facilitate the control of the degree of polymerization of the primary condensate and the degree of polymerization in the step of increasing the degree of polymerization, it is effective to add a degree of polymerization control agent. As the polymerization degree regulator, a monoamine compound and a monocarboxylic acid compound are usually used, but acetic acid, benzoic acid, stearic acid and the like are preferable. The addition amount of the polymerization regulator is 0 to 0.1 times mol, preferably 0.0001 to 0.05 mol, based on the total number of moles of the constituent monomer and dicarboxylic acid component unit and diamine component unit of the salt. Used.

The pressure-type polymerization tank for producing the primary condensate of the present invention is not particularly limited, and known ones such as a complete mixing type reaction vessel and a plug flow type reaction vessel can be used. If necessary, a multi-tank system can be used. As a method of discharging from the polymerization tank, it is preferable to discharge under a pressure of 1 to 100 kg / cm ² -G, and the pressure during the polymerization reaction can be used as it is, or can be adjusted to an arbitrary pressure with an inert gas such as N _2. It is suitable to pressurize and discharge. Further, when the primary condensate having a long discharge time or a large increase in viscosity during discharge is discharged, it is preferable to supply water or steam to the polymerization tank and to discharge under pressurized steam. It is also possible to use a metering pump such as a gear pump to adjust the discharge rate.

The primary condensate discharged from the polymerization tank can be directly charged into a crusher for crushing, or can be continuously discharged into a steel belt or a cooling drum and then continuously charged into the crusher. . It is also possible to cool the primary condensate by directly injecting compressed air or water with a shower nozzle or a spray gun before introducing the primary condensate into the pulverizer.

As the crusher, a model capable of crushing in a short time is suitable, and a pin type, a blade type, a hammer type or the like which is a rotary crusher can be arbitrarily used. The pulverization temperature is 250 ° C. or lower, preferably 200 ° C. or lower, and if it exceeds 250 ° C., there is a risk of fusion of the primary condensate inside the pulverizer. The crushed particle size may be 10 mm or less, preferably 5 mm or less, but fine powder of 0.2 mm or less is not preferable in handling. If it exceeds 10 mm, the inside of the crushed particles may be colored. further,
The primary condensate after crushing can be immediately blown into a storage silo or the like using a blower blower or a cyclone.

In the present invention, the primary condensate pulverized in this manner has a high degree of polymerization. As a method of increasing the degree of polymerization of the primary condensate, a method using a melting machine, a method of solid-phase polymerization, a method of using a melting machine, a solid-phase polymerization machine in combination, and the like can be adopted. When using a melting machine, the melting temperature is preferably in the range of 10 to 70 ° C. higher than the melting point of the primary condensate. When using a primary condensate having many terephthalic acid components and a high melting point, it is necessary to set the upper limit temperature to 370 ° C. or lower in order to prevent thermal decomposition and thermal deterioration of the polymer. As the melt extruder, an extruder or a kneader can be used, but a twin screw extruder or a twin screw kneader is preferable.

The residence time in the melting machine is not particularly limited, but it is preferably 20 seconds or longer, particularly preferably 30 seconds or longer. If the residence time is short, the degree of polymerization cannot be effectively increased, which is not preferable. It is also effective to connect two or more melting machines in series in order to lengthen the residence time and promote a high degree of polymerization. The phosphorus-based catalyst is effective for increasing the degree of polymerization, and may be added if necessary. Further, the polymer having a high degree of polymerization can be subjected to solid phase polymerization as necessary to further increase the degree of polymerization.

The solid phase polymerization may be carried out under pressure or normal pressure in the presence of an inert gas, under reduced pressure, or any combination thereof. The solid phase polymerization temperature is 130 ° C. to the melting point of the polymer or lower, preferably 170 ° C. to melting point −10 ° C., more preferably 200 ° C. to melting point −15 ° C. If the solid phase polymerization temperature is lower than 130 ° C., the reaction rate becomes slow, which is not preferable. As the solid phase polymerization time, any time until the relative viscosity of the polyamide used for a usual molded product is reached can be selected. The polymerization apparatus of the present invention is not particularly limited, and any known method can be used. Specific examples of the solid-state polymerization apparatus include a kneader, a twin-screw paddle type, a tower type, a rotating drum type, and a double-cone type solid-state polymerization apparatus.

The relative viscosity (η _r ) of the polyamide resin obtained by increasing the degree of polymerization is preferably 1.8 to 5.0. A filler can be added to the polyamide resin obtained in the present invention. The filler is glass beads, talc, kaolin, wollastonite, mica, silica, alumina,
Powdered or plate-like inorganic compounds such as kieselguhr, clay, gypsum, red iron oxide, graphite, titanium dioxide, zinc oxide, copper, stainless steel, and other polymer fibers (carbon fibers), etc., preferably glass fibers . As the glass fibers, glass fibers are generally used as a reinforcing agent for thermoplastic resins and thermosetting resins, but particularly preferred are glass rovings and glass chopped strands made from continuous long fiber strands having a diameter of about 3 to 20 μm. , Glass, etc. The blending ratio of such a filler needs to be in the range of 0 to 200 parts by weight with respect to 100 parts by weight of the polyamide, preferably more than 0 and 15 parts by weight.
The range is 0 parts by weight, particularly preferably 10 to 100 parts by weight. When the blending ratio of the filler exceeds 200 parts by weight, the fluidity at the time of melting deteriorates, and it becomes difficult to injection-mold a thin-walled molded product, and the appearance of the molded product deteriorates, which is not preferable.

There is no particular limitation on the method of adding the filler to the crystalline polyamide of the present invention, and any known method can be used. A specific example of the compounding method is a method in which a filler is dry-blended with crystalline copolyamide pellets, and the resulting mixture is melt-kneaded with a single-screw or twin-screw extruder. When the degree of polymerization is increased with an extruder, a method of side-feeding in the middle of the extruder is preferable because of high production efficiency.

In the present invention, when the primary condensate is produced,
If necessary, such as catalysts, heat resistance stabilizers, weather resistance stabilizers, plasticizers, mold release agents, lubricants, crystal nucleating agents, pigments, and other polymers Etc. can be added. These additives include heat-resistant stabilizers (hindered phenol-based, hydroquinone-based, phosphite-based and substitution products thereof, copper iodide, potassium iodide, etc.), weather resistance stabilizers (resorcinol-based, salicylate-based, benzoic acid-based Triazole type, benzophenone type, hindered amine type, etc., mold release agent and lubricant (montanic acid and its salt, its ester, its half ester, stearyl alcohol, stearamide and polyethylene wax, etc.), pigment (cadmium sulfide, phthalocyanine type compound, carbon) Black), and dyes (such as nigrosine), other polymers (other polyamides, polyesters, polycarbonates, polyphenylene ethers, polycarbonates, polyphenylene ethers, polyphenylene sulfides, liquid crystal polymers,
Polyether sulfone, ABS resin, SAN resin, polystyrene, acrylic resin, polyethylene, polypropylene, ethylene / α-olefin copolymer, ionomer resin, SBS, SEBS, etc.).

From the viewpoint of productivity, the additive compound is
It is more preferable to perform the polymerization at the same time or continuously in the melter. The addition of an antioxidant is effective for improving the color tone of the polyamide, and the addition of sodium hypophosphite and a hindered phenol-based antioxidant is particularly preferable. Sodium hypophosphite is also effective in promoting a high degree of polymerization of the primary condensate.

The polyamide of the present invention includes switches, microminiature slide switches, DIP switches, switch housings, lamp sockets, binding bands, connectors, connector housings, connector shells, IC sockets,
Coil bobbins, pobbin covers, relays, relay boxes, condenser cases, motor internal parts, small motor cases, gear cams, dancing pulleys, spacers, insulators, fasteners, buckles,
Wire clips, bicycle wheels, casters, helmets, terminal blocks, power tool housings, starter insulation parts, spoilers, canisters, radiator tanks, chamber tanks, reservoir tanks, fuse boxes, air cleaner cases, air conditioner fans,
Typical examples include terminal housings, wheel covers, intake and exhaust pipes, bearing retainers, cylinder head covers, intake manifolds, water pipe impellers, clutch releases, speaker diaphragms, heat-resistant containers, microwave oven parts, rice cooker parts, printer ribbon guides, etc. Electric / electronic related parts, automobile / vehicle related parts,
It is useful for home appliances / office electrical appliances parts, computer related parts, facsimile / copier related parts, machine related parts, and other various applications.

[0027]

EXAMPLES The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to the following examples without departing from the spirit of the invention. The properties in the examples and comparative examples were measured by the following methods. 1) Melting point (Tm) Using DSC (PERKIN-ELMER7 type), sample 8-10m
The temperature showing the maximum value of the melting curve obtained by measuring g at a temperature rising rate of 20 ° C./min was defined as Tm. 2) The physical properties of the molded product were measured by the following methods.

Tensile Strength: ASTM-D638 Bending Strength: ASTM-D790 Bending Elastic Modulus: ASTM-D790 Izod Impact Strength: ASTM-D256 Heat Distortion Temperature (HDT): ASTM-D648 Load
4.6 kgf / cm ² load 18.6 kgf / cm ² <Example 1> hexamethylene ammonium adipate
(66 salt) 15.0 kg, terephthalic acid and hexamethylenediamine salt (6T salt) 15.0 kg, benzoic acid 134 g
Then, 7.5 kg of ion-exchanged water was charged into a 0.1 m ³ batch type polymerization tank, and the atmosphere was sufficiently replaced with nitrogen.
Heating was continued under a pressure of 5 kg / cm ² -G. 3.5 hours under stirring
After the temperature was raised to 230 ° C., the ion-exchanged water heated to 180 ° C. was added to the polymerization tank at a rate of 3 l / h, and further maintained at 225 ° C. to 230 ° C. for 30 minutes to complete the reaction, Length of primary condensate from the bottom of the polymerization tank to the atmosphere 8
It was discharged at a rate of 50 kg / h onto a steel belt having a width of 0.5 m and a width of 0.5 m. Continuous primary condensate from steel belt
It is supplied to Hosokawa Micro Co., Ltd. DKA06 rotary hammer type crusher, the rotation speed is 500 rpm, and the screen hole diameter is 15
Milled using mm. A white powder having an average particle size of 1 mmφ or less was obtained. The relative viscosity of the obtained primary condensate is η _r of 1.1.
5, the melting point was 289 ° C. 100% of this primary condensate
After vacuum-drying at 24 ° C. for 24 hours, melt extrusion was performed with a bent type twin-screw extruder having a diameter of 30 mm under the temperature condition of 260 ° C. to 335 ° C. White pellets having a polymer viscosity η _r = 2.70 and a polymer melting point of 295 ° C. were obtained. 50 parts by weight of glass fiber chopped strands having a length of 3 mm and a diameter of 13 μm were dry-blended with 100 parts by weight of the pellets, and melt-mixed at a polymer melting point of + 20 ° C. in a 30 mmφ single screw extruder. This mixture was molded by an injection molding machine to prepare a test piece. Table 1 shows the results of evaluation of the obtained test pieces. <Example 2> 85 wt% aqueous solution of ε-caprolactam = 1
0.59 kg, terephthalic acid 12.36 kg, hexamethylenediamine 64.5 wt% aqueous solution 13.41 kg, benzoic acid 188 g and ion-exchanged water 7.0 kg were charged into a 0.1 m ³ batch type pressure polymerization tank and replaced with nitrogen. Was sufficiently performed, and then heating was continued under a steam pressure of 40 kg / cm ² -G.
After heating to 270 ° C. over 5 hours with stirring, while supplying ion-exchanged water heated to 240 ° C. to the polymerization tank with a metering pump at a rate of 2 l / h, it was further heated at 270 to 275 ° C. for 1 h.
Maintained and completed reaction. After discharging in the same manner as in Example 1, it was crushed by a crusher UG280 manufactured by Horai Co., Ltd. using a rotation speed of 350 rpm and a screen diameter of 12 mm,
A white powder having an average particle size of 2 mm was obtained. The melting point of this primary condensate was 303 ° C. and η _r was 1.53. 100 this
After being dried for 24 hours, the mixture was melt-extruded by the method of Example 1, compounded and molded, and evaluated. The results are shown in Table 1. <Example 3> 6.18 kg of terephthalic acid, 1 of isophthalic acid
After charging 1.48 kg, a 64.5 wt% aqueous solution of hexamethylenediamine, 19.13 kg, a 25 wt% acetic acid aqueous solution 255 g, and ion-exchanged water 6.0 kg into a 0.1 m ³ batch type polymerization tank, and performing sufficient nitrogen substitution. Water vapor pressure 40kg / cm
Heating was continued under ^2- G pressure. 270 with stirring for 5 hours
After the temperature was raised to 0 ° C., the temperature was further maintained at 270 to 275 ° C. for 1 hour to complete the reaction, and then discharge and pulverization were performed in the same manner as in Example 1. At this time, ion-exchanged water was sprayed on the steel belt at a rate of 30 kg / h using a spray gun, and the primary condensate was continuously charged into the crusher while cooling. Particle size 5mm
A white powder of φ or less was obtained. The viscosity of this primary condensate is η _r
= 1.47 and the melting point was 322 ° C. The obtained primary condensate was vacuum dried at 100 ° C. for 24 hours, then melt-extruded, compounded and molded, and evaluated. The results are shown in Table 1. <Example 4> The primary condensate polymerized in the same manner as in Example 2 was vacuum dried at 100 ° C for 24 hours, and then 7 kg of the primary condensate was placed in a biaxial kneader (KHD-0030 type) manufactured by Inoue Seisakusho, and N ₂ was added. The temperature was raised from room temperature to 250 ° C over 3 hours under blowing. After reaching 250 ° C., the solid-phase polymerization reaction was continued for another 3 hours and then cooled to room temperature. η _r = 2.75, melting point = 30
A white powder at 4 ° C. was obtained. This powder was used for compounding and molding according to the method of Example 1, and the evaluation results are shown in Table 1. <Comparative Example 1> After the primary condensate was polymerized under the same conditions as in Example 2, ion-exchanged water was placed in a stainless container having a length of 1.5 m, a width of 1.5 m and a depth of 0.6 m, and the mixture was stirred. While being discharged into water, a white precipitate was obtained. After dehydration with a vertical centrifugal dehydrator with a filter cloth, it was dried at a temperature of 110 ° C. using a twin-screw paddle dryer (NPD-1.6W, Nara Machinery Co., Ltd.). During the drying, the primary condensate began to harden like a dango, the paddle shaft was overloaded, and the motor stopped. Comparative Example 2 Polymerization and discharge were carried out under the same conditions as in Example 3. After discharging the steel belt, the primary condensate was continuously placed in a stainless container having a length of 1.5 m, a width of 1.5 m and a depth of 0.6 m without crushing. The surface of the primary condensate (lump) was colored yellow and the inside was colored brown in a short time. Comparative Examples 3 to 4 Polymerization was carried out in the same manner as in Example 1 except that the relative viscosity of the primary condensate was outside the scope of the present invention, except for the conditions shown in Table 1. The one having a low η _r of the primary condensate (Comparative Example 3) does not achieve a sufficient degree of polymerization, while the one having a high η _{r of the} primary condensate (Comparative Example 4) has stable discharge of the primary condensate. I didn't.

[0029]

[0030]

By adopting the production method of the present invention, a polyamide resin having a terephthalic acid component and having a high degree of polymerization can be efficiently and stably produced.

Claims (1)

[Claims] 1. A hexamethylene terephthalamide unit represented by the following structural formula (I): And any unit selected from the following structural formulas (II) to (IV) And the copolymerization ratio is (I) / (II) = 55 by weight.
/ 45-80 / 20 or (I) / (III) = 20/80
~ 80/20 or (I) / (IV) = 55 / 45-90
In producing a polyamide resin in the range of / 10,
Under conditions of 150 to 350 ° C., a primary condensate having a relative viscosity (η _r ) at 25 ° C. of a 1% sulfuric acid solution of 1.04 to 2.5 is polymerized, and the primary condensate is discharged from a polymerization tank to continuously 1. A method for producing a polyamide resin, which comprises pulverizing the primary condensate and then increasing the degree of polymerization of the primary condensate.