WO1996014882A1

WO1996014882A1 - Antimicrobial treatment method for automative air-conditioning system

Info

Publication number: WO1996014882A1
Application number: PCT/KR1994/000162
Authority: WO
Inventors: John Hee Hong; Mal Sik Park
Original assignee: Hyundai Motor Company
Priority date: 1994-11-11
Filing date: 1994-11-11
Publication date: 1996-05-23
Also published as: JPH09511941A; AU8117694A; EP0790838A1

Abstract

This invention relates to an automative air-conditioning system comprising air-conditioning evaporator, heater, blower and duct characterized in which plastic material of housing, well-closed pad and lining pad of air-conditioning evaporator, door pad of heater housing, blowing-fan and lining pad of blower and duct are molded by mixing the antimicrobial compound selected from isothiazolines and oxybisphenoxarsines, and aluminum material of core of the said air-conditioning evaporator core is antimicrobially treated by coating hydrophilic coloring agent mixed with the antimicrobial composition of parachlorometa xylenol.

Description

ANTIMICROBIAL TREATMENT METHOD FOR AUTOMATIVE AIR- CONDITIONING SYSTEM

FIELD OF THE INVENTION 5 This invention relates to a method of antimicrobial treatment for automative air-conditioning system and more particularly, the method of antimicrobial treatment for automative air-conditioning system wherein ; while manufacturing air-conditioning evaporator, heater, blower and duct, which are main components of the existing automative air-conditioning system, the mixture of some antimicrobial agents is applied ι c to the said automative air-conditioning system for its antimicrobial treatment in an attempt to prevent the proliferation of several fungi present in the system, thus keeping the indoor air, flowing from the said air-conditioning system, fresh and clean during the operation of cooling or heating.

i =5 BACKGROUND OF THE INVENTION

For the purpose of cooling and/or heating operation, the automative air- conditioning system consists of 4 components such as air-conditioning evaporator, heater, blower and duct, installed at the engine room in the indoor of automobile; each component of the automobile air-conditioning system is made from plastic moldings : c such as housing or pad, while metallic materials in some components.

Since the components of the automative air-conditioning system are made from the plastic or metallic materials, the propagation of bacteira or fungi are difficult under a common atmosphere.

Nevertheless, when the cooling and/or heating is to be made by the operation of 5 the automative air-conditioning system, the difference in temperature between atmosphere and the air-conditioning system causes to bring about the local blockade in each component. The indoor air flowing from the outside to the said air-conditioning system serves to make various species of bacteria or fungi fit for their living. Actually, one can easily detect the proliferation of several species of bacteria or fungi present in the automative air-conditioning system which is now under market.

According to the careful investigation of the inventor et al. , it is ascertained that several species of fungi (e.g., Aspergillus sp. ATCC 6275, Cladosporium sp., 5 Penicillum sp., Aspergillus sp., Trichoderma sp., Saccharomyces sp., Fusarium sp.,

Alternaria sp., etc.) are propagated in each component consisting of the automative air-conditioning system, as shown in Fig. 1.

More specifically, Fig. 1 demonstrates several species of fungi propagated in each component consisting of the automative air-conditioning system ; the door pad of i heater has five species of fungi [e.g., Aspergillus sp. ATCC 6275(1), Cladosporium sp.

IAM.F 517(2), Penicillum sp. ATCC 9849(3) and Penicillum sp.(4), Aspergillus sp.

ATCC 6245(5)], as shown in Fig. 1 ; the blower has Trichoderma sp.(6) as shown in

Fig. 1 ; the core of air-conditioning evaporator has five species of fungi[e.g.,

Saccharomyces sp.(7), Cladosporium sp.(8), Fusarium sp.(9), Penicillum sp.(lθ), 1 5 Alternaria sp.(l 1)] as shown in Fig. 1 ; the housing of air-conditioning evaporator has five species of fungi[e.g., Penicillum sp. ATCC 9849(12), Rhodotorula sp.(l3),

Cladosporium sp.(14) and Cladosporium sp. IAM.F 517(15), Fusarium sp. USDA

1004.1(16)] as shown in Fig. 1. The representative groups of fungi are as follows:

Aspergillus sp. ATCC 6275(1) C Cladosporium sp. IAM.F 517(2)

Penicillum sp. ATCC 9849(3)

Penicillum citrinum ATCC 9849(4)

Aspergillus sp. ATCC 6245(5)

Trichoderma sp. ATCC 9645(6) s Saccharomyces sp.(7)

Cladosporium sp. IAM.F 517(8)

Fusarium sp. USDA 1004.1(9)

Alternaria sp.(l l)

Penicillum sp. ATCC 9849(12) Rhodotorula sp.(13) Cladosporium sp.(14) Cladosporium sp. IAM.F 517(15) Fusarium sp. USDA 1004.1(16) 5 As shown in the above, the existing automative air-conditioning system has recognized some disadvantages. In that (a) when the cooling and/or heating operation is to be repeatedly made, several species of bacteria or fungi present in each component become proliferated and then, the aging or decomposition of each component in the automative air-conditioning system causes to inevitably accelerate the C proliferation of bacteria or fungi, (b) due to the multiple proliferation of bacteria or fungi, the indoor air into the automobile becomes more deteriorated, (c) due to the bacteria or fungi mixed with the indoor air, the passengers may be associated with respiratory disorders or allergic diseases.

Considering bad weather or inability of complete indoor ventilation, appropriate 5 remedies should be established in principle, even though such problems may be somewhat settled through the indoor ventilation.

Through the prolonged intensive studies and a lot of repeated tests designed to prevent the proliferation of several fungi present in the automative air-conditioning system and to keep the indoor air of the said system fresh and clean, the inventor et al. C has aware that the proliferation of fungi may be entirly prevented, if each component of the automative air-conditioning system is antimicrobially treated with specific antimicrobial agents and thus, completed the present invention thereof.

SUMMARY OF THE INVENTION The main object of this invention, to comply with those matters associated with the proliferation of several fungi present in the existing automative air-conditioning system, is to provide a new method of antimicrobial treatment designed to prevent the proliferation of several fungi present in the automative air-conditioning system and to keep the indoor atmosphere of automobile fresh and clean. The characteristics of this invention relates to an automative air-conditioning system comprising air-conditioning evaporator, heater, blower and duct characterized in which plastic material of housing, well-closed pad and lining pad of air-conditioning evaporator, door pad of heater housing, blowing - fan and lining pad of blower and 5 duct are molded by mixing the antimicrobial compound selected from isothiazolines and oxybisphenoxarsines, and aluminum material of core of the said air-conditioning evaporator core is antimicrobially treated by coating hydrophilic coloring agent mixed with the antimicrobial composition of parachlorometa xylenol.

1 C BRIEF DESCRIPTION OF THE DRAWING

Fig. 1 is a photograph demonstrating the cultured fungi collected and separated from the existing general automative air-conditioning system ; the photograph of No. (1) through No. (5) shows five species of cultured fungi collected from a door pad of heaterfe.g., Aspergillus sp. ATCC 6275(1 ), Cladosporium sp. IAM.F 517(2),

15 Penicillum sp. ATCC 9849(3) and Penicillum sp.(4), Aspergillus sp. ATCC 6245(5); The photograph of No. (6) shows Trichoderma sp.(6) collected from a blower; the photograph of No. (7) through No. ( 1 1 )] shows five species of fungi [e.g., Saccharomyces sp.(7), Cladosporium sp.(8), Fusarium sp.(9), Penicillum sp.(lθ), Alternaria sp.(l l)] collected from a core of air-conditioning evaporator ; the re photograph of No. (12) through No. (16) shows five species of fungi [e.g., Penicillum sp. ATCC 9849(12), Rhodotorula sp.(13), Cladosporium sp.(14) and Cladosporium sp. IAM.F 517(15), Fusarium sp. USDA 1004.1 (16)] collected from a housing of air- conditioning evaporator.

Fig. 2 represents test results of the antimicrobial activities concerning the

25 automative air-conditioning system under antimicrobial treatment ; the photographs of No. (17) through (23) show the antimicrobial test for a representative group of fungi collected from the automative air-conditioning system ; the photograph of No. (24) shows the antimicrobial test for the separated fungi collected from a blower of automative air-conditioning system ; the photographs of No. (25) through (29) show the antimicrobial test for the separated fungi collected from a core of the automative air- conditioning system ; the photographs of No. (30) through (34) show the antimicrobial test for the separated fungi collected from a housing of automative air-conditioning system ; the photographs of No. (35) through (39) show the antimicrobial test for the 5 separated fungi collected from a door pad of heater in the automative air-conditioning system.

Fig. 3 represents test results of the antimicrobial activities related to Candida albicans and Cladosporium after the aging test concerning the antimicrobially-treated polypropylene housing in the automative air-conditioning system, according to this i c invention ; the photographs of No. (40) and No. (41 ) show the antimicrobial test after environment aging ; the photographs of No. (42) and No. (43) show the antimicrobial test after waterproofing aging ; the photographs of No. (44) and No. (45) show the antimicrobial test after heat aging ; the photographs of No. (46) and No. (47) show the antimicrobial test after shock aging.

15 Fig. 4 represents test results of the antimicrobial activities after the aging test concerning the antimicrobially-treated pad of the automative air-conditioning system, according to this invention ; the photographs of No. (48) and No. (49) show the antimicrobial test of well-closed polyethylene pad after the aging test ; the photographs of No. (50) and No. (51) show the antimicrobial test of polyurethane door pad after the C aging test ; the photographs of No. (52) and No. (53) show the antimicrobial test of polyurethane lining pad after the aging test.

Fig. 5 represents test results of the antimicrobial activities after the aging test concerning the antimicrobially-treated core of air-conditioning evaporator of the automative air-conditioning system, according to this invention ; the photographs of 5 No. (54) and No. (55) show the 28-day culture after microbial untreatment ; the photographs of No. (56) and No. (57) show the antimicrobial test after 28-day culture of fungi's spores. DETAILED DESCRIPTION OF THE INVENTION

This invention relates to the a method of antimicrobial treatment for automative air-conditioning system designed to entirely inhibit the generation and proliferation of several species of fungi by manufacturing, through the use of antimicrobial agents, each of components consisting of the existing air-conditioning system. According to this invention, sub-components in plastic material such as housing, pad, etc. are molded by mixing the antimicrobial compounds such as isothiazolines or oxybisphenoxarsines. And a core of air-conditioning evaporator in aluminium material is antimicrobially treated by coating hydrophilic coloring agent containing parachlorometa xylenol, antimicrobial composition.

According to this invention, isothiazolines having the following chemical formula(I) of 2-n-octyl-4-isothiazoline-3-one is used as an antimicrobial agent, whilst oxybisphenoxarsine having the following chemical formula(II) of 10,10'- oxybisphenoxarsine is used as an antimicrobial agent:

(I) (ID Molecular weight: 213.34 g/mole Molecular weight: 520.2 g/mole Chemical formula: C_πH_]9NOS Chemical formula: C₂₄H₁₆As₂O₃

According to this invention, the said air-conditioning system composes of four components such as air-conditioning evaporator, heater, blower and duct ; among them, the fabrication of air-conditioning evaporator contains the housing and core in its inside, well-closed pad designed to ensure the tightness in the inside of housing, and 7 oscillation-absorbing lining pad.

According to this invention, the fabrication of housing in the said air-conditioning evaporator is made from the following process : polypropylene resin added with talc of 20wt. % is mixed with appropriate antimicrobial agents such as isothiazolines or oxybisphenoxarsines to manufacture a master batch and then, the batch is under the process of injection molding to manufacture the air-conditioning evaporator housing, having durability and antimicrobial activity.

Hence, the compound having 2-n-octyl-4-isothiazoline-3-one as isothiazolines may be used as an antimicrobial agent, whilst the compound having 10,10'- oxybisphenoxarsine as oxybisphenoxarsines may be used as an antimicrobial agent. However, if the contents of those antimicrobial agents in proportion to polypropylene resin are used in less than 0.5 wt. %, the antimicrobial effect may not be achieved and in case of its excessive use, the injected molding become poor and thus, a variety of physical properties proves to be also poor. Since the core of air-conditioning evaporator comprises a refrigerant evaporator, the antimicrobial treatment should require special consideration. Especially, considerering that the core of air-conditioning evaporator is made from aluminum material, its radiation of heat is of much significance and during the antimicrobial treatment, every care should be made not to reduce the radiation of heat. According to this invention, for appropriate antimicrobial treatment of the core in air-conditioning evaporator, the core of air-conditioning evaporator is coated by the antimicrobial coloring agent producing from mixing silicate-family hydrophilic coloring agent with parachlorometa xylenol in 0.1 ~ 1.5wt. %. Hence, when the antimicrobial coloring agent is applied to the core of air-conditioning evaporator, the core is dipped into coloring agent mixed with the said antimicrobial coloring agent and then, picked it up to continue the application by making its dried thickness 4 - 7μm.

In the case where the applied thickness of antimicrobial coloring agent is less than 4μm, the stability of applied membrane is not secured under the operation of air-conditioning evaporator where the change in temperature or humidity is very high ; the applied membrane is detached or the antimicrobial activity may not be expected due to insufficiency of antimicrobial agent. If the thickness is over lim, however, the radiation of heat in the core of air-conditioning evaporator become decreased so that a centrifuge should be desirably used so as to assure the homogeneous applied membrane 5 and to prevent the cloggedness due to the antimicrobial agents at the core of air- conditioning evaporator. To the silicate-family colouring agent, intended for the above antimicrobial colouring agent, parachlorometha xylenol may be added as an antimicrobial agent; if the content of parachlorometha xylenol is less than 0.5 wt. % of the colouring agent, the antimicrobial effect may not be achieved and if the content is i C more than 1.5 wt. %, the antimicrobial effect is quite remarkable, but the application characteristics of colouring agents becomes poor and the reducement of viscosity may lead to easy detachment of the antimicrobial membrane.

Meantime, for the purpose of ensuring the airtightness in the inside of the housing of air-conditioning evaporator, the well-closed pad is installed; to the said

15 well-closed pad, the content of isothiazolines or oxybisphenoxarsine is used in 0.2 ~ 1.0 wt. % and with the mixture of foaming agent and cross-linking agent, a master batch dissolved is pressured and molded to manufacture an foaming-type pad.

Hence, the content of the said antimicrobial agent is used in 0.2 ~ 1.0 wt. % in proportion to the whole composition; if the content is less than 0.2wt. %, the C antimicrobial effect of well-closed polyethylene pad and in case of the excessive use, the pressured molding is very poor so that the quality of pad product is deteriorated with the difficulty of molding.

Also, the lining pad of the said air-conditioning evaporator, made from a foaming urethanee material, is intended to be used for absorbing noise and oscillation 5 incurred out of the operation of air-conditioning evaporator. The antimicrobial treatment of the lining pad is made in the following manner; prior to the molding, main ingredients such as polyol and isocyanate are mixed with, water, foaming agent, surfactant and amine compound, catalyst such as organic metal, etc. Thus, to the said mixture of well-known raw material resin, the antimicrobial agent such as oxybisphenoxarsines is added in 0.2 ~ 1.0 wt. % to produce a foamed molding pad.

Through the above processes, the antimicrobially treated housing, core, well- closed pad and lining pad of air-conditioning evaporator are manufactured. Based upon the existing structure, these components are fabricated from the well-known method to 5 comprise the air-conditioning evaporator as part of the air-conditioning system according to this invention.

According to the present invention, the antimicrobial treatment is to be made to the heater, another main component of automative air-conditioning system for the purpose of proliferation of several fungi; a high temperature of dried air generated by i o the heater makes the fungi difficult to proliferate, but when the heater is not operated, some fungi coming from the outside is proliferated on the door pad of heater. Therefore, the antimicrobial treatment for the door pad of heater in carried out in the same method as the case of lining pad of said air-conditioning evaporator, the treated door pad is assembled in heater. 15 The blower, which is fan-flowing the cooled or heated air through the air- conditioning evaporator or heater manufactured in accordance with the present invention into the inside of automobile, should be antimicrobially treated. The blower consists of housing, fan and lining pad, but dusts from the outside are liable to be piled on these components. Since the piled dusts are placed on the spot where outer 0 air and cooled (or heated) air are met, the great difference in temperature and humidity akes the fungi fit for their living.

According to the present invention, the antimicrobial treatment of housing and blowing-fan of blower is made in the same manner as do in the above; as a basic material, the housing of blower uses polypropylene adding a talc in 20wt. %, whilst the 5 blowing-fan uses polypropylene adding a talc in 15wt. %. Then, by mixing the said isothiazoline or oxybisphenoxarsine in 0.5 ~ 1.5wt. %, a master batch is manufactured and through the common method, the injected molding is performed to obtain a final object.

Hence, the reason on limited use of antimicrobial agent in case of the housing of the said air-conditioning evaporator is applicable to the components of blower.

Also, the lining pad of blower comprises a foaming urethane item, manufactured from a foaming process after the antimicrobial treatment as in the same manner as do in the lining pad of the said air-conditioning evaporator. 5 Meantime, the duct, air tunnel of the antimicrobially treated automative air- conditioning system, comprises a blow-molding product of polyethylene material; the piled dusts make the fungi to proliferate in duct due to difference in temperature, the antimicrobial treatment must be taken; as a basic material, polypropylene is added with the said isothiazoline or oxybisphenoxarsine in 0.5 - 1.5 t. %, a master batch is i o manufactured and through the common method, the blow molding is performed to obtain the antimicrobially treated duct.

Unlike the existing system, the air-conditioning system consisting of each of antimicrobially treated component under a common fabrication method may inhibit the proliferation of fungi.

1 5 As described in the above, the manufactured air-conditioning evaporator, heater, blower and duct, which are main components of the existing automative air- conditioning system, is under antimicrobial treatment by mixing a certain amount of antimicrobial agents to the existing molding materials. Thus, the system can demonstrate their antimicrobial activities without change in physical properties C compared with the existing components. To ascertain whether any species of fungi is proliferated on each of components related to the antimicrobially treated air- conditioning system, several antimicrobial tests were made. The results showed that the antimicrobial activities proved good and the tests for physical properties demonstrated no severe problem. 5 Therefore, in the case where the antimicrobially treated air-conditioning system is applied to the existing automobiles according to the present invention, any contamination of fungi may be prevented in the automative air-conditioning system, thus flowing fresh and clean air into the inside of automobile and maintaining the comfortable environment of inside without any bad odor. Hereafter, the present invention is described in more detail based upon the following examples but the invention is not limited to the examples.

EXAMPLE 1 Antimicrobial treatment for air-conditioning evaporator 5 With the addition of talc in 20 wt.%, polypylene in 100 wt. part was prepared and then, the mixture was mixed with 2-n-octyl-4-isothiazoline-3-one in 0.1 wt. part for its pelletization in the compressor heated at 230"C . Thenceforth, a master batch is manufactured and at the temperature of 230 , , the housing of air-conditioning evaporator was manufactured by injection molding. ι o On the one hand, in order to coat the existing cores of air-conditioning evaporator (Manufacturer: Halla Cement and Doowon Co., Korea) consisting of an aluminum alloy, a hydrophilic coloring agent (Brandname: LN 4534 manufactured by Parkerizing Co. in Japan) in 100 wt. part was added with parachlorometha xylenol in 0.1 wt. part so as to prepare antimicrobial coating and then, the core of said air-conditioning

15 evaporator was dipped, centrifuged at 450 - 500rpm to shake off the materials deposited onto the core of air-conditioning evaporator for 1 minute, and dried at 178 t for 20 minutes. Thenceforth, the core of air-conditioning evaporator whose surface is deposited with the antimicrobial coating of 5.3μm was manufactured.

On the other hand, after mixing low-density polyethylene resin in 30 ~ 40 wt. C part and polypropylene resin in 50 ~ 60 wt. part with azobisformamide in 1 wt. part as a foaming agent and dianyl peroxide in less than 1 wt. % as a cross-linking agent, 10, lO'-oxybisphenoxarsine in 0.5 wt. part was also added into the mixture and then, the molding by compressor was made at the temperature of 200'C . Following the foaming and molding process, a well-closed polyethylene pad related to the air- 5 conditioning evaporator treated with the antimicrobial coating was manufactured.

Further, a foaming polyurethane resin(Manufacturer: Cheil urethanee Co., Korea) in 10 wt. part added with 10, lO'-oxybisphenoxarsine in 0.5 wt. pan was mixed homogeneously and a lining pad was manufactured following the foaming and molding process. 9 /1

12 In accordance with a common method, the fabrication of the above antimicrobially treatment items was made to manufacture an air- conditioning evaporator.

5 EXAMPLE 2 - 5

These EXAMPLES were performed in the same manner as did in the above EXAMPLE 1 and air-conditioning evaporators were manufactured in parallel with the coating thickness of antimicrobial coloring agent as shown in Table 1.

i θ Table 1.

Quantity (wt. part)

Component Antimicrobial agent

EX 1 EX 2 EX3 EX4 EX 5

Housing 2-n-octyl-4-isothiazoline 0.3 0.5 1.0 1.5 2.0 -3-one^{(1 >}

10, 10'-oxybisphenoxarsine⁽²⁾ 0.3 0.5 1.0 1.5 2.0

Core Parachlorometha xylenol 0.1 0.5 1.0 2.0 3.0

(Antimicrobial Coating thickness(wn) 4.5 4.5 5 5.4 6 coloring agent)

Well-closed pad 2-n-octyl-4-isothiazoline-3-one 0.1 0.3 0.5 1.0 2.0

10, lO'-oxybisphenoxarsine 0.1 0.3 0.5 1.0 1.5

Lining pad 2-n-octyl-4-isothiazoline-3-one 0.1 0.3 0.5 1.0 1.5 5 10, lO'-oxybisphenoxarsine 0.1 0.3 0.5 1.0 1.5

Note : (1) Skane M-8 (manufacturer: Rohm & Haas Co. in U.S.A.) was used; (2) Vinyzene (manufacturer: Morton Co.) was used.

The following items are officially approved from the Environmental 0 Protection

Agency of U.S.A. as antimicrobial agents to ensure the safety to the human body. EXAMPLE 6 Antimicrobial treatment of heater

A foaming polyurethane resin(Manufacturer: Cheil urethanee Co., Korea) in 10 wt. part, added with 10, 10' -oxybisphenoxarsine in 0.5 wt. part, was mixed homogeneously and a door pad of heater was manufactured following; the foaming and 5 molding process at the temperature of 20 ~ 301-: . A heater was manufactured using the existing heater (Manufacturer: Halla Co., Korea) whose door pad was antimicrobially treated.

EXAMPLE 7 - 10 i o These EXAMPLES were performed in the same manner as did in the above

EXAMPLE 6 and heaters were manufactured in parallel with the composition of antimicrobial agent as shown in Table 2.

Table 2.

1 5

Quantity (wt. part)

Component Antimicrobial agent

EX 6 EX 7 EX 8 EX 9 EX 10

Door pad 10, lO'-oxybisphenoxarsine 0.1 0.3 0.5 1.0 3.0 of heater

EXAMPLE 11 Antimicrobial treatment of blower

To the well-known raw materials of polypropylene resin (Manufacturer: Honam Petrochemical and Hyundai Petrochemical, Korea) in 100 wt. part added with talc in 20 wt. %, 10, lO'-oxybisphenoxarsine in 0.5 wt. part was mixed to manufacture a master batch. Then, the batch was injected at the cylinder temperature of 230 Xl so as to manufacture the blowing housing. And in the same manner as above, the blower fan was manufactured using the well-known polypropylene resin added with talc in 15 wt. . Further, in order to manufacture a lining pad of blower, a foaming urethanee resin in 10 wt. part , a same material as used in the EXAMPLE 1, was mixed with 10, 10' -oxybisphenoxarsine of 1.5 wt. part and then, the mixture was foamed and molded at the room temperature of 20 - 23 "C . A blower was assembled by each components as the above.

EXAMPLE 12 - 15

These EXAMPLES were performed in the same manner as do in the above EXAMPLE 11 and blowers were manufactured in parallel with the composition of antimicrobial agent as shown in Table 3.

Table 3.

Quantity (wt. part)

Component Antimicrobial agent EXl f EX12 EX13 EX14 EX15

Housing 10, 10' -oxybisphenoxarsine 0.3 0.5 1.0 1.5 2.0

Blowing-fan 10, 10' -oxybisphenoxarsine 0.3 0.5 1.0 1.5 2.0

EXAMPLE 16 Antimicrobial treatment of duct

In order to manufacture a duct, polypropylene resin (manufacturer: Honam Petrochemical in Korea) in 100 wt. part was added with 10, lO'-oxybisphenoxarsine of 0.5 wt. part, mixed homogeneously, and molded the mixture by blow molder at the temperature of 190 "C .

EXAMPLE 17 - 20

These EXAMPLES were performed in the same manner as did in the above EXAMPLE 14 and ducts were manufactured in parallel with the composition of antimicrobial agent as shown in Table 4 Table 4.

Quantity (wt. part)

Component Antimicrobial agent

EX16 EX17 EX18 EX19 EX20

Duct 10, 10' -oxybisphenoxarsine 0.3 0.5 1.0 1.5 2.0

TEST 1

The main components fabricated in accordance with the above EXAMPLES 1 , 6, 11, 16 respectively were manufactured by the air-conditioning system of "Hyundai Motor 1991 -type Elantra" and based upon partial specimens, the antimicrobial test was made thereof. [Antimicrobial test]

An agar plate method(KSK 0692) was utilized as Halo Test. The test strains were collected from each part of the air-conditioning system of the Hyundai Motor 1991 -type Elantra having a pilot milege of 30,000 km in the period of one year (from March 1991 to February 1992). A representative group of strains includes

Aspergillus niger, Penicillum citrinum, Aureobasidiu pullulans, Candida albicans, Fusarium moniliforme, Cladosporium cucumerinum, Saccharomyces cerevisiae, etc.

According to this invention, the housing manufactured from the EXAMPLE 1 was denominated as specimen A and B by adding 2-n-octyl-4-isothiazoline-3-on in the EXAMPLE 1, 2; the housing was denominated as specimen D, E by adding 10, lO'-oxybispenoxarsine; in order to compare the effect of two antimicrobial agents as above, another specimen was denominated as specimen C by adding another sample of antimicrobial agent. The size of each specimen was made by 1 x 1cm and the antimicrobial test was made on agar plate medium.

Test strains were prepared in the following method; the strains were inoculated into a medium of American Association of Textile Chemists and Colorists(AATCC) by using Ami platinum loop under the medium condition of pH 7.0 - 7.2 and then, cultured at the temperature of 37 Xl for 24 hours.

While sterilized samples of strain were placed on a plate of agar medium, a necessary amount of A ATCC agar was dissoluted in a test tube or flask, cooled at 45 "C , and cultured for 24 hours. In proportion to 150ml of AATCC agar, 1 ml of the cultured strains are injected and after 15 minutes, the mixture was used as a medium. After placing the test strains on the medium, the plate medium was cultured at the temperature of 37 ^*C for 24 hours.

At the floor of the medium where culture was completed, the clear zone(halo) at the neighborhood of sample strains was observed to evaluate the antimicrobial test.

In order to evaluate the antimicrobial activity, a antimicrobial test was conducted to the strains separated and collected from a blower, a core and housing of air-conditioning evaporator, and door pad of heater respectively as well as to the said representative group of strains and the results of antimicrobial activity were as shown in the following Table 5.

Table 5.

Test strains Sample A Sample B Sample C Sample D Sample E Photo

(Fig. 2)

Aspergillus niger ++ +++ + ++ ++ 17

Penicillum citrinum +++ +++ ++ +++ +++ 18

Aureobasidium +++ +++ +++ ++ +++ 19 pullulans

Candida albicans ++ +++ ++ ++ ++ 20

Fusarium moniliforme ++ +++ + ++ ++ 21 Table 5-1.

Test strains Sample Sample Sample Sample Sample * Photo

A B C D E (Fig. 2)

5

Cladosporim cucumerinum ++ +++ + ++ ++ 22

Saccharomyces cerevisiae +++ +++ ++ +++ +++ 23 i o Strain separated from blower - +++ 24

Strain 1, separated from core ++ ++ - ++ ++ 25 of air-conditioning evaporator

15 Strain 2, separated from core +++ +++ + ++ ++ 26 of air-conditioning evaporator

Strain 3, separated from core ++ ++ - ++ ++ 27 of air-conditioning evaporator

__ C

Strain 4, separated from core ++ +++ + ++ ++ 28 of air-conditioning evaporator

Strain 5, separated from core +++ +++ + +++ +++ 29

25 of air-conditioning evaporator

Strain 1 , separated from housing ++ +++ + ++ ++ 30 of air-conditioning evaporator

30 Strain 2, separated from housing ++ -t-+ + ++ ++ 31 of air-conditioning evaporator

Strain 3, separated from housing +++ +++ +++ +++ +++ 32 of air-conditioning evaporator

35

Strain 4, separated from housing +++ +++ - +++ +++ 33 of air-conditioning evaporator

Strain 5, separated from housing +++ +++ + +++ +++ 34

40 of air-conditioning evaporator

Strain 1, separated from door ++ +++ - ++ ++ 35 pad of heater 5 Strain 2, separated from door +++ +++ - +++ +++ 36 pad of heater

Strain 3, separated from door +++ -t-++ + +++ ++ 37 pad of heater C

Strain 4, separated from door ++ +++ - ++ ++ 38 pad of heater

Strain 5, separated from door +++ +++ + +++ +++ 39 5 pad of heater

* The above photo shows the design illustrated in Fig. 2. The above Table demonstrates antimicrobial acivities by calculating the formation scope of lower region in accordance with Paragraph 2, Article 8 of Korean Standard K 0692-1991.

+++ : Excellent (more than 3mm in the formation scope of lower region), 5 ++ : Good (more than l~3mm in the formation scope of lower region), + : Fair (less than 1mm in the formation scope of lower region), : Poor (no formation of lower region).

TEST 2 i c Among the antimicrobially-treated components, the antimicrobial activity test on a housing product in polypropylene resin was made after aging test. The test conditions of antimicrobial activity were established in the same manner as did in the above Test 1 and the microbial activity on Candida albicans and Cladosporium cucumerinum were made. About five kinds of housing specimen A, B, C, D, and E,

15 which are antimicrobial specimens of polypropylene manufactured from the above EXAMPLES 1, 2, 3, 4 and 5, several aging tests such as environment aging, water¬ proof aging, heat aging and shock aging were made so as to determine the antimicrobial activity under the following conditions and the results were as shown in Table 6 - 9. The aging conditions were as follows: 0 (Environment aging)

A specimen was left at 80 X. - 90 C for 3 -5 hours, maintained it at -40 - - -50 t for 3 hours, and maintained again at 3512 ~ 45 X. , relative humidity of 98% for 15 - 20 hours. After the above environmental change three times, the aging specimen was prepared. 5 (Heat aging)

A specimen was left in an oven at 8012 - 90 "C for 7 -20 days and then, the aging specimen was prepared. (Water-proof aging)

A specimen was left in a flowing water at 3012 - 3512 for 10 - 15 days and then, the aging specimen was prepared. (Shock aging) A specimen was left at -3012 - 4512 for 15 - 20 hours and immediately, it was dipped into a warm water at 7012 - 9012 for 5 minutes. Then, the aging specimen was prepared.

Table 6. Results of antimicrobial activity after the environment aging

Test strains Sample Sample Sample Sample Sample * Photo

A B C D E (Fig. 3)

Candida albicans ++ +++ - + + (40)

Cladosporium cucumerinum ++ +++ + ++ ++ (41)

*+++ : Excellent, ++ : Good, + : Fair, - : Poor

Table 7. Results of antimicrobial activity after the water-proof aging

Test strains Sample Sample Sample Sample Sample * Photo A B C D E (Fig. 3)

Candida albicans +++ + ++ (42) Cladosporium cucumerinum + +++ - + + (43)

*+++ : Excellent, ++ : Good, + : Fair, - : Poor

Table 8. Results of antimicrobial activity after the heat aging

Test strains Sample Sample Sample Sample Sample * Photo A B C D E (Fig. 3)

Candida albicans + +++ ++ (44) Cladosporium cucumerinum + ++ + + + (45)

*+++ : Excellent, ++ : Good, + : Fair, - : Poor Table 9. Results of antimicrobial activity after the shock aging

Test strains Sample Sample Sample Sample Sample * Photo A B C D E (Fig. 3)

Candida albicans + +++ - + ++ (46)

Cladosporium cucumerinum + +++ - + ++ (47)

*+++ : Excellent, ++ : Good, + : Fair, - : Poor

The photographs of the said Table 6 - 9 show Fig. 3, thus demonstrating the remarkable antimicrobial activity after various kinds of aging tests.

TEST 3

Among the antimicrobially-treated components, the antimicrobial activity tests on polyethylene pad, polyurethane pad, and polyurethane lining pad were made after aging test respectively. The test conditions of antimicrobial activity were established in the same manner as did in the above Test 1 and the microbial activity on Candida albicans and Cladosporium cucumerinum were made. About well-closed polyethylene pad of air-conditioning evaporator, polyurethane door pad, and polyurethane lining pad of blower manufactured from the above EXAMPLES 3, several aging tests such as environment aging , water-proof aging, heat aging and shock aging were made so as to determine the antimicrobial activity under the following conditions and the results were as shown in Table 10 -11. Hence, the aging conditions are the same as did in the above Test 2. As shown in the following Table 10 - 1 1, the control was not provided with the aging condition. Table 10. Well-closed pad of polyethylene

Test strains Control Waterproof Heat aging Environment Photo aging aging (Fig. 4)

5

Aspergillus niger + ++ + + (48)

Penicillum citήnum + + + + (49)

10

*+++ : Excellent, ++ : Good, + : Fair, - : Poor

Table 11. Door pad of polyurethane

1 5

2 o Aspergillus niger + + + (50)

Penicillum ciirinum + • + + (51)

"_ * +++ : Excellent, ++ : Good, + : Fair, - : Poor

Table 12. Lining pad of polyurethane

3

Aspergillus niger ++ ++ + (52) 35

Penicillum citrinum ++ ++ + + (53)

*+++ : Excellent, ++ : Good, + : Fair, - : Poor

40

The photographs of the said Table 10 - 12 show Fig. 3 and the antimicrobial activity was ascertained as good as the control group.

5 TEST 4

Among the antimicrobially treated components, the antimicrobial test on the core of air-conditioning evaporator was performed based on a method of JIS Z2911; according to this method, spore solution was dipped into a test specimen, cultured at 28 ± 2 "C for 28 days and at 7-day intervals, the growth of molds were observed. Hence, used was the test specimen where the antimicrobial colouring agent was applied to the core manufactured from the above EXAMPLE 1. The results were as shown in the following Table 13.

Table 13.

Specimen 7-day culture 14-day culture 21-day culture 28-day culture Photo (Fig. 5)

(A) X X X X (54)(55)

(B) X X X X (56)(57)

* (A) : In the case where mold spores were cultured into the antimicrobially treated specimen; (B) : In the case where mold spores and the mixing solution of organic materials according to JIS Z291 1 were cultured into the antimicrobially treated specimen; X : Hyphae were not confirmed in the specimen.

The mold spores used in the Test 4 were as follows:

( 1 ) Aspergillus niger IFO 6341

(2) Penicillum citrinum IFO 6352

(3) Chaetomin m globosum ATCC 6205

(4) Cladosporium cladosporioides IFO 6348

(5) Rhizopus oryzae IFO 31005

In order to ascertain the test results, the microscope based photographs on the surface of core in Fig. 5 revealed that the remarakable antimicrobial activity after the treatment of antimicrobial agent, as shown in a microscope based photograph showing 28-day culture in non-treatment of antimicrobial agent and a microscope based photograph related to specimen (A) and (B). TEST 5

In order to observe the physical property of housing molding product in parallel with the concentration of antimicrobial agent for the housing of air-conditioning evaporator manufactured from the above EXAMPLES 1 - 5, the physical property on each of housing specimen was measured and the results were as shown in the following Table 14.

Table 14.

EXAMPLE

Items Unit Testing method Control

(Non- treatment)

Melting index g/lO min ASTM D1238 10.1 10.3 10.4 11.0 11.5 12.5

Density g/cc ASTM D1505 1.07 1.07 1.07 1.06 1.06 1.10

Thermal stress t ASTM D648 131 131 130.5 129 125 121 temperature

Yielding point kg c«i ASTM D638 354 352 350 345 340 330 tensile stress

Elongation rate % ASTM D638 54 54 54 52.5 50.0 48

Flex stength kg/on¹ ASTM D790 520 519 518 515 510 502

Flex elasticity kg/αii ASTM D790 27,00 rate

IZOD impact kg • on/ cm ASTM D256 5.0 4.9 4.9 4.5 4.0 3.6 strength

The IZOD impact strength was measured at room temperature.

As shown in the above Table 14, the antimicrobially treated components demostrated the excellent antimicrobial activity and various kinds of physical properties proved good in comparison with the control group in non-treatment.

Claims

WHAT IS CLAIMED IS :

1. An antimicrobial treatment method for automative air-conditioning system comprising air-conditioning evaporator, heater, blower and duct characterized in

5 which plastic material of housing, well-closed pad and lining pad of air-conditioning evaporator, door pad of heater, housing , blowing - fan and lining pad of blower and duct are molded by mixing antimicrobial compound selected from isothiazolines and oxybisphenoxarsines, and aluminum material of core of the said air-conditioning evaporator core is antimicrobially treated by l o coating hydrophilic coloring agent mixed with the antimicrobial composition of parachlorometha xylenol.

2. The antimicrobial treatment method for automative air-conditioning system as defined in claim 1, wherein the said antimicrobial compound of

15 isothiazolines is 2-n-octyl-4-isothiazoline-3-one.

3. The antimicrobial treatment method for automative air-conditioning system as defined in claim 1, wherein said antimicrobial compound of oxybisphenoxarsines is 10,10 -oxybisphenoxarsine.

4. The antimicrobial treatment method for automative air-conditioning system as defined in claim 1, wherein the housing of said air-conditioning evaporator is manufactured by injected molding in such a manner to mix a polypropylene resin containing 20% of talc employed as main material, 5 with the antimicrobial substance in 0.5 - 1.5 wt. %.

5. The antimicrobial treatment method for automative air-conditioning system as defined in claim 1, wherein the well-closed pad of said air-conditioning evaporator is manufactured by foamed molding in such a manner to mix polyethylene resins employed as main material, with the antimicrobial substance in 0.2 - 1.0 wt. %.

6. The antimicrobial treatment method for automative air-conditioning system 5 as defined in claim 1 , wherein the door pad of said heater is manufactured by foamed molding in such a manner to mix polyurethane resin employed as main material with the antimicrobial substance in 0.2 - 1.0 wt. %.

7. The antimicrobial treatment method for automative air-conditioning system i c as defined in claim 1 , wherein the housing and blowing fan of said blower are manufactured by injected molding in such a manner to mix each of polypropylene resin employed as main material, with the antimicrobial substance in 0.2 - 1.0 wt. %.

15 8. The antimicrobial treatment method for automative air-conditioning system as defined in claim 1, wherein the lining pads of both said air-conditioning evaporator and blower are manufactured by mixing polyurethane resin employed as main material, with the antimicrobial substance in 0.2 - 1.0 wt.

%.

9. The antimicrobial treatment method for automative air-conditioning system as defined in claim 1, wherein said duct is manufactured by blow molding in such a manner to mix polyethylene resin employed as main material, with the antimicrobial substance in 0.5 - 1.5 wt. %. 5

10. The antimicrobial treatment method for automative air-conditioning system as defined in claim 1, wherein said antimicrobial colouring agent is to be mixed the hydrophilic coloring agent with said parachlorometha xylenol in 0.5 - 1.5 wt. %.

11. The antimicrobial treatment method for automative air-conditioning system as defined in claim 1, wherein said antimicrobial coloring agent is coated on the core surface of said air - conditioning evaporator as a dipping method, thus making its dried thickenss by 4 - 7μm.

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