A high melt strength regenerated polyester fiber fine denier yarn and its production process

Abstract

The present invention provides a high melt strength regenerated polyester fine denier yarn and a production process thereof, relating to the field of fiber production technology. The high melt strength regenerated polyester fine denier yarn, the raw material components by weight include: 100 parts of regenerated polyester and 0.5-5 parts of POSS modified polyurethane; the POSS modified polyurethane is obtained by reacting a polyester polyol with a polyisocyanate compound and then reacting with a monoamino POSS. Preferably, the functionality of one of the polyester polyol and the polyisocyanate compound is greater than 2. The high melt strength regenerated polyester fine denier yarn of the present invention has the characteristics of high melt strength, high tensile strength, etc., and can significantly improve the stability and production efficiency of spinning.

Description

Technical Field

[0001] The invention belongs to the technical field of fiber production and relates to a high-melt-strength regenerated polyester fine-denier yarn and a production process thereof. Background Art

[0002] Recycled polyester, mainly recycled PET, has been widely used in the fields of footwear, clothing, packaging materials, etc. Compared with virgin polyester, the melt viscosity of recycled polyester in the molten state is higher, and a relatively higher melt spinning temperature is required. For example, the melt spinning temperature of virgin polyester is generally 250-270°C, and the melt spinning temperature of recycled polyester is generally 280-290°C. However, recycled polyester is also prone to broken fibers when melt-spinning at this melt temperature. One of the reasons is that the melt strength of recycled polyester is not high enough compared to virgin polyester. In the prior art, in order to improve the melt strength of polyester, chain extenders are generally added. The chain extenders react in situ with the end groups of the polyester molecular chain in the molten state to expand the molecular weight of the polyester and improve the melt strength, but at the same time, they also increase the melt viscosity.

[0003] Therefore, for recycled polyester, it is an urgent problem to improve its melt strength while avoiding the increase of melt viscosity to achieve better melt spinning effect. Summary of the Invention

[0004] In order to solve the above technical problems, the present invention provides a high melt strength regenerated polyester fine denier yarn and a production process thereof.

[0005] The technical solutions of the present invention are as follows:

[0006] A high melt strength regenerated polyester fine denier yarn, the raw material components comprising, by weight, 100 parts of regenerated polyester and 0.5-5 parts of POSS modified polyurethane;

[0007] The POSS modified polyurethane is obtained by reacting polyester polyol with a polyisocyanate compound and then reacting with monoamino cage-shaped polysilsesquioxane.

[0008] Preferably, the intrinsic viscosity of the recycled polyester is 0.6-0.85 dL / g.

[0009] Preferably, the functionality of at least one of the polyester polyol and the polyisocyanate compound is 2.

[0010] More preferably, the functionality of the polyester polyol is 2, and the functionality of the polyisocyanate compound is greater than 2;

[0011] Alternatively, the functionality of the polyester polyol is greater than 2, and the functionality of the polyisocyanate compound is 2.

[0012] Preferably, the molar ratio of the OH groups in the polyester polyol to the NCO groups in the polyisocyanate compound is 1:1.2-2.

[0013] Preferably, the number average molecular weight of the polyester polyol is 600-3000.

[0014] Preferably, the structure of the monoamino cage-shaped polysilsesquioxane is shown in the following formula (1):

[0015] R 1 NHR 2 R 3 n-1 (SiO 1.5 ) n (1)

[0016] where R 1 is H, C1-C4 alkyl, cyclopentyl, cyclohexyl or C6-C12 substituted cycloalkyl, R 2 is absent, C1-C6 alkylene or C2-C8 substituted alkylene, R 3 Selected from C1-C8 alkyl, n=6, 8, 10 or 12.

[0017] More preferably, the monoamino cage-type polysilsesquioxane is selected from one or a combination of 3-aminopropylheptamethyl cage-type octasilsesquioxane and 3-aminopropylheptabutyl cage-type octasilsesquioxane.

[0018] Preferably, the ratio of the sum of the molar numbers of hydroxyl groups in the polyester polyol and the amino groups in the monoamino cage-type polysilsesquioxane to the molar number of NCO groups in the polyisocyanate compound is 0.9-1.05:1.

[0019] A process for preparing high melt strength regenerated polyester fine denier yarn according to any of the above technical solutions comprises: mixing, melt spinning, cooling, stretching, shaping, oiling and winding;

[0020] The cooling is firstly natural cooling in a windless area and then cooling in a ventilated area.

[0021] The beneficial effects of the present invention are:

[0022] (1) The present invention adopts the additive--POSS modified polyurethane mode to improve the melt strength of recycled polyester, and does not affect its melt viscosity, is conducive to reducing the breakage rate of melt spinning, and improves the melt spinning effect. POSS modified polyurethane has a structure in which the end group is POSS and the middle is polyester-polyurethane, which can be a linear structure or a branched structure. The polyester-polyurethane structure in the middle provides good compatibility with recycled polyester, and the POSS structure at both ends is large in volume, providing good mutual entanglement with recycled polyester macromolecule, thereby improving the melt strength of recycled polyester. However, due to the good compatibility of POSS modified polyurethane with recycled polyester, the melt viscosity of recycled polyester is not substantially affected.

[0023] (2) The preparation method of the POSS modified polyurethane of the present invention is relatively simple. A terminal isocyanate prepolymer is obtained by reacting a polyester polyol with a polyisocyanate compound, and then reacting with a monoamino cage-shaped polysilsesquioxane. By adjusting the molecular weight of the polyester polyol, the molar ratio of the polyester polyol to the polyisocyanate compound, the functionality of the polyester polyol and the polyisocyanate compound, etc., the obtained POSS modified polyurethane has the effect of improving the melt strength of the recycled polyester. DETAILED DESCRIPTION

[0024] The technical solution of the present invention is further illustrated and described below through specific implementation methods.

[0025] In order to improve the melt strength of recycled polyester and have a lower impact on its melt viscosity, on the one hand, the present invention provides a high melt strength recycled polyester fine denier yarn, the raw material components comprising, by weight: 100 parts of recycled polyester and 0.5-5 parts of POSS modified polyurethane;

[0026] POSS modified polyurethane is obtained by reacting polyester polyol with polyisocyanate compound and then reacting with monoamino cage-shaped polysilsesquioxane.

[0027] POSS is an inorganic core composed of the silicon-oxygen skeleton alternately connected by Si-O and an organic group connected to the Si atom in the top corner, and its three-dimensional size is between 1~3nm, belonging to organic-inorganic hybrid nano material. In order to improve the melt strength of recycled polyester, the cage-type polysilsesquioxane (POSS) of physical mixing is introduced in recycled polyester among the present invention. In POSS modified polyurethane, the POSS structure at end can form stronger mutual entanglement and intermolecular action between the macromolecular chain of recycled polyester, and middle polyester-polyurethane and recycled polyester have good compatibility. Therefore, POSS modified polyurethane can improve the melt strength of recycled polyester, and also has certain promoting effect for the mechanical strength of recycled polyester. And, by polyester-polyurethane and recycled polyester having good compatibility, good plasticizing is played in molten state, and the adverse effect to melt viscosity brought owing to introducing POSS modified polyurethane is reduced.

[0028] In a preferred embodiment of the present invention, the intrinsic viscosity of the recycled polyester is 0.6-0.85 dL / g. For example, the intrinsic viscosity of the recycled polyester can be any value among 0.6 dL / g, 0.65 dL / g, 0.7 dL / g, 0.75 dL / g, 0.8 dL / g, 0.85 dL / g, or any value in between, without particular limitation. Furthermore, the intrinsic viscosity of the recycled polyester can be 0.7-0.85 dL / g.

[0029] In a preferred embodiment of the present invention, at least one of the polyester polyol and the polyisocyanate compound has a functionality of 2. For polyester polyols, the functionality refers to the number of hydroxyl groups, such as a polyester diol having a functionality of 2. For polyisocyanate compounds, the functionality refers to the number of NCO groups, such as a diisocyanate compound having a functionality of 2. Polyester polyols and / or polyisocyanate compounds with two functionalities are advantageous in forming a certain linear structure.

[0030] In a more preferred embodiment of the present invention, the functionality of the polyester polyol is 2, and the functionality of the polyisocyanate compound is greater than 2;

[0031] Alternatively, the functionality of the polyester polyol is greater than 2, and the functionality of the polyisocyanate compound is 2.

[0032] When the functionality of the polyester polyol and the functionality of the polyisocyanate compound are both 2, what is formed in theory is a linear polyester-polyurethane structure; when one of the functionality is greater than 2, a polyester-polyurethane structure with a certain branched structure can be formed, and then after reacting with POSS, the POSS modified polyurethane formed is a branched structure, which can form more and stronger mutual entanglement and intermolecular effects with the recycled polyester polymer chain, and improve the melt strength and mechanical strength of the recycled polyester. In the present invention, when the functionality of the polyester polyol or the functionality of the polyisocyanate compound is greater than 2, such as the polyester polyol can be a combination of polyester triol or polyester diol and polyester triol, and the polyisocyanate compound can be a trimer, such as HDI trimer, or a combination of diisocyanate compound and trimer. The polyisocyanate compound may be a diisocyanate compound and / or a triisocyanate compound. The diisocyanate may be an aliphatic diisocyanate, such as isophorone diisocyanate IPDI, 4,4'-dicyclohexylmethane diisocyanate HMDI, 3,3'-dicyclohexylmethane diisocyanate, hexamethylene diisocyanate HDI, 1,4-cyclohexane diisocyanate, methylcyclohexane diisocyanate, norbornane dimethylene isocyanate and L-lysine diisocyanate, and the triisocyanate compound may be an HDI trimer, etc. For example, in order to obtain a polyisocyanate compound with a functionality > 2, a combination of a diisocyanate compound and a trimer can be used. The weight ratio of the diisocyanate compound and the trimer in the combination is not particularly limited. For example, the weight ratio can be 10:1-1:10, such as 10:1, 9:1, 7:1, 5:1, 4:1, 2:1, 1:1, 1:2, 1:3, 1:5, 1:7, 1:9, 1:10, etc.

[0033] In a preferred embodiment of the present invention, the molar ratio of the OH groups in the polyester polyol to the NCO groups in the polyisocyanate compound is 1:1.2-2. For example, the molar ratio of the OH groups in the polyester polyol to the NCO groups in the polyisocyanate compound can be any value among 1:1.2, 1:1.3, 1:1.4, 1:1.5, 1:1.6, 1:1.7, 1:1.8, 1:1.9, 1:2, etc., or any value in between, without particular limitation. Furthermore, the molar ratio of the OH groups in the polyester polyol to the NCO groups in the polyisocyanate compound can be 1:1.3-2.

[0034] In a preferred embodiment of the present invention, the number average molecular weight of the polyester polyol is 600-3000. The polyester polyol can be a polycarbonate polyol, a polycaprolactone polyol, or the like, such as a polycarbonate diol, a polycarbonate triol, a polycaprolactone diol, or a polycaprolactone triol, or can be one or a combination of two or more thereof. For example, in order to obtain a polyester polyol with a functionality greater than 2, a combination of a polycarbonate diol and a polycarbonate triol can be used. The weight ratio of the polycarbonate diol to the polycarbonate triol in the combination is not particularly limited, for example, the weight ratio can be 10:1-1:10, such as 10:1, 9:1, 7:1, 5:1, 4:1, 2:1, 1:1, 1:2, 1:3, 1:5, 1:7, 1:9, 1:10, or the like.

[0035] Monoamino cage-type polysilsesquioxane (monoamino POSS) refers to a cage-type polysilsesquioxane having only one amino group in its molecular structure, which can be either a primary amino group or a secondary amino group, and preferably, in addition to the amino group, the monoamino cage-type polysilsesquioxane does not contain any other functional groups that can react with the NCO group at 100°C. One amino group in the monoamino POSS reacts with the prepolymer, bonding to the end group of the prepolymer and introducing the POSS structure. In a preferred embodiment of the present invention, the structure of the monoamino POSS is shown in the following formula (1):

[0036] R 1 NHR 2 R 3 n-1 (SiO 1.5 ) n (1)

[0037] where R 1 is H, C1-C4 alkyl, cyclopentyl, cyclohexyl or C6-C12 substituted cycloalkyl, R 2 is absent, C1-C6 alkylene or C2-C8 substituted alkylene, R 3 is selected from C1-C8 alkyl, n=6, 8, 10 or 12. That is, in the monoamino POSS structure of the present invention, the amino group is R 1 NHR 2 -Formally embodied.

[0038] In a more preferred embodiment of the present invention, the monoamino cage-type polysilsesquioxane is selected from one or a combination of 3-aminopropyl heptamethyl cage-type octapolysilsesquioxane (3-aminopropyl heptamethyl POSS) and 3-aminopropyl heptabutyl cage-type octapolysilsesquioxane (3-aminopropyl heptabutyl POSS), which is reported in the prior art.

[0039] In the preferred embodiment of the present invention, the ratio of the sum of the mole number of amino in hydroxyl and monoamino POSS and the NCO group mole number in the polyisocyanate compound is 0.9-1.05:1. Adopt above-mentioned mol ratio, can make in the POSS modified polyurethane, OH, amino and NCO group react completely as far as possible. Further, the ratio of the sum of the mole number of amino in hydroxyl and monoamino POSS and the NCO group mole number in the polyisocyanate compound can be 0.95-1.02:1 in the polyester polyol, for example, ratio can be any value in 0.95:1,0.96:1,0.97:1,0.98:1,0.99:1,1:1,1.01:1,1.02:1 etc. or any value between, without particular restrictions.

[0040] In another aspect, the present invention provides a process for preparing high-melt-strength regenerated polyester fine-denier filaments as described in any of the above-mentioned technical solutions, comprising: mixing, melt spinning, cooling, stretching, shaping, oiling, and winding. Cooling is performed by first cooling naturally in a windless zone and then in a ventilated zone. This prevents the freshly spun fine-denier filaments from being quenched, thereby preventing them from becoming brittle and hindering subsequent processing. The melt spinning temperature can be 280-285°C.

[0041] The technical solution of the present invention is further described and illustrated below based on various embodiments. Unless otherwise specified, the parts in the following embodiments are parts by weight.

[0042] Preparation Example 1-7 Preparation of POSS modified polyurethane

[0043] Preparation Example 1

[0044] The molar ratio of polycarbonate diol to HDI is 1:1.6, and the ratio of the sum of the molar numbers of OH groups in polycarbonate diol and amino groups in 3-aminopropylheptamethyl POSS to the molar number of NCO groups in HDI is 1:1.

[0045] Polycarbonate diol (number average molecular weight 1000) and HDI are added to a reaction vessel, stirred and mixed at room temperature and reacted until the content of NCO groups in the reaction system remains unchanged to obtain a prepolymer; 3-aminopropylheptamethyl POSS is further added to the prepolymer, and stirring is continued at room temperature until the reaction is complete to obtain a POSS-modified polyurethane.

[0046] Preparation Example 2

[0047] The difference between this preparation example and Preparation Example 1 is that in Preparation Example 1, the polycarbonate diol was adjusted to an equimolar combination of polycarbonate diol (number average molecular weight 1000) and polycarbonate triol (number average molecular weight 1200) at a weight ratio of 4:1. The remaining steps remained unchanged.

[0048] Preparation Example 3

[0049] The difference between this preparation example and Preparation Example 1 is that in Preparation Example 1, HDI was adjusted to an equimolar combination of HDI and HDI trimer at a weight ratio of 5:1. The remaining steps remained unchanged.

[0050] Preparation Example 4

[0051] The difference between this preparation example and Preparation Example 1 is that in Preparation Example 1, the molar ratio of polycarbonate diol to HDI is adjusted to 1:1.3. The remaining steps remain unchanged.

[0052] Preparation Example 5

[0053] The difference between this preparation example and Preparation Example 1 is that in Preparation Example 1, the molar ratio of polycarbonate diol to HDI is adjusted to 1:2. The remaining steps remain unchanged.

[0054] Preparation Example 6

[0055] The difference between this preparation example and Preparation Example 1 is that in Preparation Example 1, the ratio of the sum of the molar numbers of OH groups in the polycarbonate diol and the amino groups in 3-aminopropylheptamethyl POSS to the molar number of NCO groups in HDI was adjusted from 1:1 to 0.95:1. The remaining steps remained unchanged.

[0056] Preparation Example 7

[0057] The difference between this preparation example and Preparation Example 1 is that in Preparation Example 1, the ratio of the sum of the molar numbers of OH groups in the polycarbonate diol and the amino groups in 3-aminopropylheptamethyl POSS to the molar number of NCO groups in HDI was adjusted from 1:1 to 1:1.02. The remaining steps remained unchanged.

[0058] Example 1

[0059] Recycled polyester, intrinsic viscosity 0.75dL / g, filtered through a vibrating screen and melt filter to remove impurities.

[0060] 100 parts of the recycled polyester after impurity removal and 0.5 parts of the POSS modified polyurethane of Preparation Example 1 were mixed in a mixer, melt-spun at 282°C, cooled (after cooling in a 15 cm windless zone and then cooling in a ventilation zone), stretched at a stretching ratio of 4, shaped at 120°C, oiled and wound to obtain 50D / 144f ultrafine denier regenerated polyester fiber.

[0061] Example 2

[0062] The difference between this embodiment and Example 1 is that in Example 1, the amount of POSS modified polyurethane in Preparation Example 1 is adjusted from 0.5 parts to 1.5 parts. The remaining steps remain unchanged.

[0063] Example 3

[0064] The difference between this embodiment and Example 1 is that in Example 1, the amount of POSS modified polyurethane in Preparation Example 1 is adjusted from 0.5 parts to 3.5 parts. The remaining steps remain unchanged.

[0065] Example 4

[0066] The difference between this embodiment and embodiment 1 is that in embodiment 1, the amount of POSS modified polyurethane in preparation example 1 is adjusted from 0.5 parts to 5 parts. The remaining steps remain unchanged.

[0067] Comparative Example 1

[0068] The recycled polyester after impurities removal in Example 1.

[0069] Comparative Example 2

[0070] The difference between this comparative example and Example 1 is that in Example 1, the POSS modified polyurethane of Preparation Example 1 is replaced by octamethyl POSS of equal weight. The remaining steps remain unchanged.

[0071] Comparative Example 3

[0072] The difference between this comparative example and Example 1 is that in Example 1, the POSS modified polyurethane of Preparation Example 1 is replaced by an equal weight of polyester-polyurethane. The remaining steps remain unchanged.

[0073] The preparation method of polyester-polyurethane is as follows:

[0074] The molar ratio of polycarbonate diol, anhydrous ethanol and HDI is 1:3:1.6.

[0075] Polycarbonate diol (number average molecular weight 1000) and HDI are added to a reaction vessel, stirred and mixed at room temperature and reacted until the content of NCO groups in the reaction system remains unchanged. Anhydrous ethanol is continued to be added and reacted until no NCO groups are detected in the reaction system. The temperature is raised to 90°C to remove excess anhydrous ethanol to obtain the product.

[0076] Example 5

[0077] Recycled polyester, intrinsic viscosity 0.75dL / g, filtered through a vibrating screen and melt filter to remove impurities.

[0078] 100 parts of the recycled polyester after impurity removal and 2 parts of the POSS modified polyurethane of Preparation Example 1 were mixed in a mixer, melt-spun at 282°C, cooled (after cooling in a 15 cm windless zone and then cooling in a ventilation zone), stretched at a stretching ratio of 3.7, shaped at 120°C, oiled and wound to obtain 50D / 144f ultrafine denier regenerated polyester fiber.

[0079] Example 6

[0080] The difference between this embodiment and Example 5 is that in Example 5, the POSS modified polyurethane of Preparation Example 1 is replaced by an equal weight of the POSS modified polyurethane of Preparation Example 2. The remaining steps remain unchanged.

[0081] Example 7

[0082] The difference between this embodiment and Example 5 is that in Example 5, the POSS modified polyurethane of Preparation Example 1 is replaced by an equal weight of the POSS modified polyurethane of Preparation Example 3. The remaining steps remain unchanged.

[0083] Example 8

[0084] The difference between this embodiment and Example 5 is that in Example 5, the POSS modified polyurethane of Preparation Example 1 is replaced by an equal weight of the POSS modified polyurethane of Preparation Example 4. The remaining steps remain unchanged.

[0085] Example 9

[0086] The difference between this embodiment and Example 5 is that in Example 5, the POSS modified polyurethane of Preparation Example 1 is replaced by an equal weight of the POSS modified polyurethane of Preparation Example 5. The remaining steps remain unchanged.

[0087] Example 10

[0088] The difference between this embodiment and Example 5 is that in Example 5, the POSS modified polyurethane of Preparation Example 1 is replaced by an equal weight of the POSS modified polyurethane of Preparation Example 6. The remaining steps remain unchanged.

[0089] Example 11

[0090] The difference between this embodiment and Example 5 is that in Example 5, the POSS modified polyurethane of Preparation Example 1 is replaced by an equal weight of the POSS modified polyurethane of Preparation Example 7. The remaining steps remain unchanged.

[0091] Performance Testing

[0092] Relative melt strength: The melt strength of the melt at 280°C was tested using a melt strength tester. The melt strength of the recycled polyester in Comparative Example 1 was set to 1. The relative melt strengths of the remaining embodiments and comparative examples were the ratio of the tested melt strength to the melt strength of the recycled polyester in Comparative Example 1.

[0093] Melt viscosity: measured at 280°C using a cone-plate viscometer with a shear rate of 10,000 s -1 .

[0094] Tensile strength: tested according to the method of GB / T3916-2013.

[0095] The results are shown in Table 1 below.

[0096] Table 1

[0097]

[0098]

[0099] From the data results in Table 1 above, it can be seen that the present invention adds POSS modified polyurethane to the recycled polyester, which can significantly improve the melt strength and tensile strength of the recycled polyester and has a relatively low impact on the melt viscosity.

[0100] During the melt spinning process of the regenerated polyester of Comparative Example 1 and the high-melt-strength regenerated polyester of Example 2, the average yarn breakage rate was 0.5 per hour and the waste rate was 12.5% ​​in Comparative Example 1, while the average yarn breakage rate was 0.08 per hour and the waste rate was 1.0% in Example 2. This indicates that the high-melt-strength regenerated polyester of Example 2 significantly improves the stability and production efficiency of fine-denier yarn spinning.

[0101] As described above, the basic principles, main features, and advantages of the present invention are shown and described. Those skilled in the art should understand that the present invention is not limited to the above-described embodiments. The above-described embodiments are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. In other words, equivalent changes and modifications made within the scope of the present invention and the contents of the specification should still fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A high melt strength regenerated polyester fine denier yarn, characterized in that: The raw material components include, by weight: 100 parts of recycled polyester and 0.5-5 parts of POSS modified polyurethane; The regenerated polyester and the POSS modified polyurethane are mixed and melt-spinned to obtain the high melt strength regenerated polyester fine denier fiber; The POSS modified polyurethane is obtained by reacting polyester polyol and polyisocyanate compound and then reacting with monoamino cage-shaped polysilsesquioxane; The molar ratio of the OH group in the polyester polyol to the NCO group in the polyisocyanate compound is 1:1.2-2.

2. The high melt strength regenerated polyester fine denier fiber according to claim 1, characterized in that: The intrinsic viscosity of the recycled polyester is 0.6-0.85 dL / g.

3. The high melt strength regenerated polyester fine denier fiber according to claim 1, characterized in that: The functionality of at least one of the polyester polyol and the polyisocyanate compound is 2.

4. The high melt strength regenerated polyester fine denier fiber according to claim 3, characterized in that: The functionality of the polyester polyol is 2, and the functionality of the polyisocyanate compound is greater than 2; Alternatively, the functionality of the polyester polyol is greater than 2, and the functionality of the polyisocyanate compound is 2.

5. The high melt strength regenerated polyester fine denier fiber according to claim 1, characterized in that: The number average molecular weight of the polyester polyol is 600-3000.

6. The high melt strength regenerated polyester fine denier fiber according to claim 1, characterized in that: The monoamino cage-type polysilsesquioxane is selected from one or a combination of 3-aminopropyl heptamethyl cage-type octasilsesquioxane and 3-aminopropyl heptabutyl cage-type octasilsesquioxane.

7. The high melt strength regenerated polyester fine denier fiber according to claim 1, characterized in that: The ratio of the sum of the molar numbers of hydroxyl groups in the polyester polyol and amino groups in the monoamino cage-shaped polysilsesquioxane to the molar number of NCO groups in the polyisocyanate compound is 0.9-1.05:

1.

8. A process for preparing the high melt strength regenerated polyester fine denier yarn according to any one of claims 1 to 7, characterized in that: include: Mixing, melt spinning, cooling, stretching, shaping, oiling and winding; The cooling is firstly natural cooling in a windless area and then cooling in a ventilated area.

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