A moisture-crosslinkable ethylene-vinyl acetate composition and a method for producing the same

Abstract

The present application relates to a kind of adhesive base materials, the purpose is to provide a kind of moisture crosslinking ethylene-vinyl acetate composition and its production method, as the base raw material in woodworking adhesive, it can be effectively used in edge sealing and crosslinking type bonding glue layer in covering.The technical scheme is a kind of moisture crosslinking ethylene-vinyl acetate composition, by the following components and corresponding weight parts are composed of:ethylene-vinyl acetate polymer 65-80 parts;Vinyl copolymer 5-10 parts;Silane oligomer 9-15 parts;Organic silane 5.4-9.4 parts;Peroxide initiator 0.2-0.4 parts;Antioxidant 0.2-0.4 parts.

Description

Technical Field

[0001] This invention relates to an adhesive base material, specifically a moisture-crosslinkable ethylene-vinyl acetate composition and its preparation method. Background Technology

[0002] Ethylene-vinyl acetate polymer resin (EVA) is an odorless, non-toxic, semi-transparent granular low-melting-point polymer. The synthesized hot melt adhesive has low viscosity and good flowability. Overall, it has the advantages of good adhesion, good flexibility, and good heat flowability. However, it also has the disadvantages of low strength, poor heat resistance, poor resistance to fatty oils, and inability to be used as a structural adhesive.

[0003] Ordinary EVA hot melt adhesive is sensitive to temperature, and the melting-solidification process is reversible. Therefore, it is not stable at high temperatures and easily softens and loses its stickiness even if it does not melt when heated.

[0004] EVA resin is an essential basic resin raw material in woodworking adhesives. In order to better improve the high-temperature resistance of ordinary EVA resin in EVA woodworking adhesives, it is very important to develop a more efficient and convenient silane-modified moisture-curable crosslinking ethylene-vinyl acetate resin (EVA). Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the above-mentioned background technology and provide a moisture-crosslinkable ethylene-vinyl acetate composition and its preparation method, which can be used as a basic raw material in woodworking adhesives and can be effectively used for edge sealing and coating of crosslinked adhesive layers.

[0006] The technical solution of this invention is:

[0007] A moisture-crosslinkable ethylene-vinyl acetate composition, comprising the following components and corresponding parts by weight:

[0008]

[0009] The vinyl copolymer is an ethylene-acrylic acid copolymer resin.

[0010] The silane oligomer is an acyloxysilane oligomer.

[0011] The organosilane is an allyl macrocyclic polyalkoxysilane.

[0012] The peroxide initiator is di-tert-butylperoxyisopropylbenzene.

[0013] The antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0014] A method for preparing a moisture-crosslinkable ethylene-vinyl acetate composition comprises the following steps:

[0015] (1) Add ethylene-vinyl acetate polymer, ethylene-acrylic acid copolymer resin, acyloxysilane oligomer, allyl macrocyclic polyalkoxysilane and antioxidant sequentially to a reactor heated to 130℃~158℃ and mix thoroughly under vacuum for 60min~80min.

[0016] (2) After mixing evenly, heat the reactor to 179-188℃, add di-tert-butyl peroxide isopropylbenzene, and carry out a stirring crosslinking grafting reaction; and evacuate the vacuum, maintaining a negative pressure of 0.7 MPa to 0.9 MPa, and react for 5-10 minutes to obtain a moisture-crosslinkable ethylene-vinyl acetate composition.

[0017] The grafted composition after the reaction in step (2) is placed in an aluminum foil vacuum bag and sealed for later use.

[0018] The preferred ethylene-vinyl acetate polymer (EVA) is model V-6110S from Zhejiang Petrochemical Co., Ltd.

[0019] The ethylene-containing acrylic copolymer is preferably produced by ExxonMobil under the trademark Escor. TM Model 5200;

[0020] The preferred silane oligomer is the acyloxysilane oligomer JH-OP1705 from Hubei Jianghan New Material Co., Ltd.

[0021] The preferred organosilane is allyl macrocyclic polyalkoxysilane JH-A596, manufactured by Hubei Jianghan New Materials Co., Ltd.

[0022] The preferred peroxide initiator is di-tert-butyl peroxide isopropylbenzene PX14SFL from AkzoNobel Peroxide (Ningbo) Co., Ltd.

[0023] The antioxidant is preferably BASF pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] Irganox 1010.

[0024] Compared with the prior art, the present invention has the following technical effects:

[0025] 1. The moisture-curable crosslinking ethylene-vinyl acetate (EVA) composition provided by the present invention is used to be added to ethylene-vinyl acetate wood edge banding adhesive to form moisture-curable crosslinking EVA wood edge banding adhesive. During the subsequent application of adhesive to the wood panel edge banding, it crosslinks with moisture in the air to form a network structure crosslinked adhesive layer, which can improve the chemical crosslinking adhesive layer between the wood panel and the edge banding strip, enhance the structure, and greatly improve the bonding strength and high temperature resistance of the EVA wood edge banding adhesive.

[0026] Ordinary EVA wood edge banding adhesive has poor high-temperature resistance and can generally only be used in environments below 60℃, and cannot be used in humid environments. The 180° peel strength of the edge banding strip is an important indicator for evaluating its quality. Generally speaking, the peel strength of edge banding strips should meet the following standards: 1. PVC edge banding strip: bonding strength with the substrate ≥ 1.5 N / cm; 2. ABS edge banding strip: bonding strength with the substrate ≥ 1.2 N / cm; 3. Acrylic edge banding strip: bonding strength with the substrate ≥ 2.0 N / cm.

[0027] Woodworking edge banding adhesives using a moisture-curable crosslinking ethylene-vinyl acetate (EVA) composition as the base resin exhibit extremely high peel strength. During use, the moisture in the air reacts with the silane to form a crosslinking layer, significantly improving resistance to thermal cycling, heat, water, solvents, and weathering. Simultaneously, it greatly enhances the bonding strength between the wood and the edge banding strip, effectively extending the service life of the woodworking edge banding strip. Furthermore, it meets the requirements of ethylene-vinyl acetate polymer (EVA) woodworking adhesives for forming a chemically crosslinked structural layer between edge banding strips.

[0028] 2. The moisture-crosslinkable ethylene-vinyl acetate (EVA) composition provided by the present invention has good thermal stability, high UV resistance and degradation resistance, as well as moisture-crosslinkable reactivity. It can effectively meet the requirements of high and low temperature resistance and weather resistance in woodworking adhesives. After use, the combined woodworking adhesive absorbs moisture and silanes from the air and undergoes a crosslinking reaction to form a crosslinked network adhesive layer, which meets the requirements of long-term stable use in natural environment.

[0029] 3. Technical specifications of the moisture-crosslinkable ethylene-vinyl acetate (EVA) composition provided by this invention:

[0030] name Indicator value range <![CDATA[Density, [g / cm 3 > 0.89±0.05 Melt viscosity, 190℃ [mPa.s] 20000±3000 Softening point [°C] 70±2 Glass transition temperature Tg DSC [°C] -30±2 Detailed Implementation

[0031] This invention uses ethylene-vinyl acetate polymer (EVA), vinyl copolymers, silane oligomers, organosilanes, and antioxidants as raw materials. The mixture is melted and homogenized in a reactor, and di-tert-butyl peroxide isopropylbenzene (BIPB) peroxide initiator is added. Grafting is completed within a specific reaction temperature and time. After passing inspection, the mixture is released and cooled, and then sealed in aluminum foil vacuum bags. The reactor is heated to 130℃~158℃, and ethylene-vinyl acetate polymer (EVA), vinyl copolymers, silane oligomers, organosilanes, and antioxidants are added sequentially. The mixture is thoroughly mixed under vacuum for 60-80 minutes. After homogenization, the reactor temperature is raised to 179℃-188℃, di-tert-butyl peroxide (BIPB) is added, stirred, and vacuumed. The vacuum level is maintained at a negative pressure of 0.7 MPa~0.9 MPa, and the reaction time is 5-10 minutes to obtain a moisture-crosslinkable ethylene-vinyl acetate composition.

[0032] During the manufacturing process, the viscosity of the composition can be adjusted by using ethylene-vinyl acetate polymers (EVA) with different melt indices. Silane oligomers can be acyloxysilane oligomers or acyloxyvinylsilane oligomers, mainly used to adjust the compatibility of various composite materials. Organosilanes can be allyl macrocyclic polyalkoxysilanes or vinylsilanes grafted onto ethylene-vinyl acetate compositions. Silane grafted modified compositions are used as part of the base material in the later sealing adhesive formulation. The final formulated adhesive can undergo a moisture crosslinking reaction when exposed to moisture in the air during use.

[0033] Therefore, in 100 parts by weight: ethylene-vinyl acetate polymer (EVA) content is 65-80 parts, ethylene-acrylic acid copolymer content is 5-10 parts, acyloxysilane oligomer content is 9-15 parts, allyl macrocyclic polyalkoxysilane content is 5.4-9.4 parts, di-tert-butyl peroxide isopropylbenzene content is 0.2-0.4 parts, and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] content is 0.2-0.4 parts.

[0034] This invention provides a method for manufacturing a moisture-crosslinkable ethylene-vinyl acetate (EVA) composition:

[0035] At a reactor temperature of 130℃~158℃, ethylene-vinyl acetate polymer (EVA), ethylene-acrylic acid copolymer, acyloxysilane oligomer, allyl macrocyclic polyalkoxysilane, and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] are added sequentially to the reactor. The mixture is thoroughly blended under vacuum for 60-80 minutes. After uniform mixing, the reactor temperature is raised to 179℃-188℃, di-tert-butyl peroxide is added, stirred, and vacuum is applied. The vacuum degree is maintained at a negative pressure of 0.7 MPa~0.9 MPa, and the reaction time is 5-10 minutes to obtain a moisture-crosslinkable ethylene-vinyl acetate composition.

[0036] The present invention will be explained in detail below with reference to the embodiments, but the scope of protection is not limited to the embodiments. Specific Implementation

[0038]

[0039] All data in the table are by weight.

[0040] The manufacturing method of Example 1 is as follows: At a reactor heating temperature of 137°C, ethylene-vinyl acetate polymer (EVA), ethylene-acrylic acid copolymer, acyloxysilane oligomer, allyl macrocyclic polyalkoxysilane, and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] are added sequentially to the reactor. The mixture is thoroughly mixed under vacuum for 75 minutes. After homogeneous mixing, the reactor temperature is raised to 186°C, di-tert-butyl peroxide is added, stirred, and vacuum is applied, maintaining a negative pressure of 0.75 MPa. The reaction time is 6 minutes to obtain a moisture-crosslinkable ethylene-vinyl acetate composition.

[0041] The manufacturing method of Example 2 is as follows: At a reactor heating temperature of 130°C, ethylene-vinyl acetate polymer (EVA), ethylene-acrylic acid copolymer, acyloxysilane oligomer, allyl macrocyclic polyalkoxysilane, and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] are added sequentially to the reactor. The mixture is thoroughly mixed under vacuum for 70 minutes. After homogeneous mixing, the reactor temperature is raised to 184°C, di-tert-butyl peroxide is added, stirred, and vacuum is applied, maintaining a negative pressure of 0.9 MPa. The reaction time is 10 minutes to obtain a moisture-crosslinkable ethylene-vinyl acetate composition.

[0042] The manufacturing method of Example 3 is as follows: At a reactor heating temperature of 144°C, ethylene-vinyl acetate polymer (EVA), ethylene-acrylic acid copolymer, acyloxysilane oligomer, allyl macrocyclic polyalkoxysilane, and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] are added sequentially to the reactor. The mixture is thoroughly mixed under vacuum for 60 minutes. After homogeneous mixing, the reactor temperature is raised to 188°C, di-tert-butyl peroxide is added, stirred, and vacuum is applied, maintaining a negative pressure of 0.7 MPa. The reaction time is 5 minutes to obtain a moisture-crosslinkable ethylene-vinyl acetate composition.

[0043] The manufacturing method of Example 4 is as follows: At a reactor heating temperature of 158°C, ethylene-vinyl acetate polymer (EVA), ethylene-acrylic acid copolymer, acyloxysilane oligomer, allyl macrocyclic polyalkoxysilane, and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] are added sequentially to the reactor. The mixture is thoroughly mixed under vacuum for 80 minutes. After homogeneous mixing, the reactor temperature is raised to 179°C, di-tert-butyl peroxide is added, stirred, and a vacuum is maintained at a negative pressure of 0.8 MPa. The reaction time is 7 minutes to obtain a moisture-crosslinkable ethylene-vinyl acetate composition.

[0044] The manufacturing method of Example 5 is as follows: At a reactor heating temperature of 151°C, ethylene-vinyl acetate polymer (EVA), ethylene-acrylic acid copolymer, acyloxysilane oligomer, allyl macrocyclic polyalkoxysilane, and pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] are added sequentially to the reactor. The mixture is thoroughly mixed under vacuum for 65 minutes. After homogeneous mixing, the reactor temperature is raised to 181°C, di-tert-butyl peroxide is added, stirred, and vacuum is applied, maintaining a negative pressure of 0.85 MPa. The reaction time is 8 minutes to obtain a moisture-crosslinkable ethylene-vinyl acetate composition.

[0045] The five sample products were tested, and the results are as follows:

[0046] Indicator Name Example 1 Example 2 Example 3 Example 4 Example 5 <![CDATA[Density, [g / cm 3 > 0.89 0.89 0.89 0.89 0.89 Melt viscosity, 190℃ [mPa.s] 15800 19800 20100 21600 25800 Softening point [°C] 67 71 71 70 73 Glass transition temperature Tg DSC [°C] -28 -32 -30 -28 -25

[0047] Practical application test in the formulation of ethylene-vinyl acetate polymer (EVA) wood edge banding adhesive.

[0048] Application Example 1

[0049] Ethylene-vinyl acetate polymer (EVA) wood edge banding adhesive Proportion Example 1 Composition 40％ Hydrogenated petroleum resin (Henghe HM-1000) 18％ Heavy calcium carbonate (1200 mesh) 30％ Rosin pentaerythritol ester 145A 10.5％ 3-(methacryloyloxy)propyltrimethoxysilane 1％ Dibutyltin dilaurate 0.2％ antioxidants 0.3％

[0050] In a reactor at a temperature of 150℃-170℃, the following materials were added in sequence: hydrogenated petroleum resin (Henghe HM-1000), rosin pentaerythritol ester 145A, the composition of Example 1, heavy calcium carbonate, 3-(methacryloyloxy)propyltrimethoxysilane, and antioxidant. The mixture was stirred thoroughly and a vacuum was drawn with a negative pressure of 0.05 MPa to 0.09 MPa. After stirring evenly for 120 minutes, dibutyltin dilaurate was added and stirred for 10 minutes before the finished wood sealing adhesive was released.

[0051] Application Example 1: Tests were conducted on the bonding of finished wood edge banding adhesive to PVC edge banding strips, ABS edge banding strips, and acrylic edge banding strips. The tests were carried out after 24 hours of storage. The test results of Application Example 1 are as follows.

[0052]

[0053] Application Example 1: The finished wood edge banding adhesive was tested to bond wood with PVC edge banding strips, ABS edge banding strips, and acrylic edge banding strips. The test was conducted after 168 hours of storage. The test results of Application Example 1 are as follows.

[0054]

[0055] Application Example 2

[0056]

[0057]

[0058] In a reactor at a temperature of 150℃-170℃, the following materials were added in sequence: hydrogenated petroleum resin (Henghe HM-1000), rosin pentaerythritol ester 145A, the composition of Example 2, heavy calcium carbonate, 3-(methacryloyloxy)propyltrimethoxysilane, and antioxidant. The mixture was stirred thoroughly and a vacuum was drawn with a negative pressure of 0.05 MPa to 0.09 MPa. After stirring evenly for 120 minutes, dibutyltin dilaurate was added and stirred for 10 minutes before the finished wood sealing adhesive was released.

[0059] Application Example 2: Tests were conducted on the bonding of finished wood edge banding adhesive to PVC edge banding strips, ABS edge banding strips, and acrylic edge banding strips. The tests were carried out after 24 hours of storage. The test results of Application Example 2 are as follows.

[0060]

[0061] Application Example 2: The finished wood edge banding adhesive was tested to bond wood with PVC edge banding strips, ABS edge banding strips, and acrylic edge banding strips. The test was conducted after 168 hours of storage. The test results of Application Example 2 are as follows.

[0062]

[0063] Application Example 3

[0064] Ethylene-vinyl acetate polymer (EVA) wood edge banding adhesive Proportion Example 3 Composition 40％ Hydrogenated petroleum resin (Henghe HM-1000) 18％ Heavy calcium carbonate (1200 mesh) 30％ Rosin pentaerythritol ester 145A 10.5％ 3-(methacryloyloxy)propyltrimethoxysilane 1％ Dibutyltin dilaurate 0.2％ antioxidants 0.3％

[0065] In a reactor at a temperature of 150℃-170℃, the following materials were added in sequence: hydrogenated petroleum resin (Henghe HM-1000), rosin pentaerythritol ester 145A, the composition of Example 3, heavy calcium carbonate, 3-(methacryloyloxy)propyltrimethoxysilane, and antioxidant. The mixture was stirred thoroughly and a vacuum was drawn with a negative pressure of 0.05 MPa to 0.09 MPa. After stirring evenly for 120 minutes, dibutyltin dilaurate was added and stirred for 10 minutes before the finished wood sealing adhesive was released.

[0066] Application Example 3: Tests were conducted on the bonding of finished wood edge banding adhesive to PVC edge banding strips, ABS edge banding strips, and acrylic edge banding strips. The tests were carried out after 24 hours of storage. The test results of Application Example 3 are as follows.

[0067]

[0068] Application Example 3: The finished wood edge banding adhesive was tested to bond wood with PVC edge banding strips, ABS edge banding strips, and acrylic edge banding strips. The test was conducted after 168 hours of storage. The test results of Application Example 3 are as follows.

[0069]

[0070] Application Example 4

[0071] Ethylene-vinyl acetate polymer (EVA) wood edge banding adhesive Proportion Example 4 Composition 40％ Hydrogenated petroleum resin (Henghe HM-1000) 18％ Heavy calcium carbonate (1200 mesh) 30％ Rosin pentaerythritol ester 145A 10.5％ 3-(methacryloyloxy)propyltrimethoxysilane 1％ Dibutyltin dilaurate 0.2％ antioxidants 0.3％

[0072] In a reactor at a temperature of 150℃-170℃, the following materials were added in sequence: hydrogenated petroleum resin (Henghe HM-1000), rosin pentaerythritol ester 145A, the composition of Example 2, heavy calcium carbonate, 3-(methacryloyloxy)propyltrimethoxysilane, and antioxidant 1010. The mixture was stirred thoroughly and a vacuum was drawn with a negative pressure of 0.05 MPa to 0.09 MPa. After stirring evenly for 120 minutes, dibutyltin dilaurate was added and stirred for 10 minutes before the finished wood sealing adhesive was released.

[0073] Application Example 4: Tests were conducted on the bonding of finished wood edge banding adhesive to PVC edge banding strips, ABS edge banding strips, and acrylic edge banding strips. The tests were carried out after 24 hours of storage. The test results of Application Example 4 are as follows.

[0074]

[0075] Application Example 4: Tests were conducted on the bonding of finished wood edge banding adhesive to PVC edge banding strips, ABS edge banding strips, and acrylic edge banding strips. The tests were carried out after 168 hours of storage. The test results of Application Example 4 are as follows.

[0076]

[0077] Application Example 5

[0078] Ethylene-vinyl acetate polymer (EVA) wood edge banding adhesive Proportion Example 5 Composition 40％ Hydrogenated petroleum resin (Henghe HM-1000) 18％ Heavy calcium carbonate (1200 mesh) 30％ Rosin pentaerythritol ester 145A 10.5％ 3-(methacryloyloxy)propyltrimethoxysilane 1％ Dibutyltin dilaurate 0.2％ antioxidants 0.3％

[0079] In a reactor at a temperature of 150℃-170℃, the following materials were added in sequence: hydrogenated petroleum resin (Henghe HM-1000), rosin pentaerythritol ester 145A, the composition of Example 5, heavy calcium carbonate, 3-(methacryloyloxy)propyltrimethoxysilane, and antioxidant. The mixture was stirred thoroughly and a vacuum was drawn with a negative pressure of 0.05 MPa to 0.09 MPa. After stirring evenly for 120 minutes, dibutyltin dilaurate was added and stirred for 10 minutes before the finished wood sealing adhesive was released.

[0080] Application Example 5: Tests were conducted on the bonding of finished wood edge banding adhesive to PVC edge banding strips, ABS edge banding strips, and acrylic edge banding strips. The tests were carried out after 24 hours of storage. The test results of Application Example 5 are as follows.

[0081]

[0082] Application Example 5: Tests were conducted on the bonding of finished wood edge banding adhesive to PVC edge banding strips, ABS edge banding strips, and acrylic edge banding strips. The tests were carried out after 168 hours of storage. The test results of Example 5 are as follows.

[0083]

[0084] The test data after adhesive application in the above five application examples clearly show that application examples 2, 3, and 4 can meet the standard for edge banding peel strength.

[0085] 1. PVC edge banding: Connection strength with substrate ≥ 1.5 N / cm;

[0086] 2. ABS edge banding: Connection strength with substrate ≥ 1.2 N / cm;

[0087] 3. Acrylic edge banding strip: Connection strength with substrate ≥2.0N / cm. It significantly improves the high-temperature resistance of wood edge banding adhesive and achieves moisture cross-linking and curing performance.

[0088] In application examples 1 and 5, the peel strength between the wood and the edge banding strip after gluing is insufficient, and delamination is likely to occur at high temperatures in the initial stage, which does not meet the requirements for peel strength and high temperature resistance of wood edge banding adhesive.

[0089] The ethylene-vinyl acetate wood adhesives described in Examples 2 to 4 above exhibit satisfactory results.

[0090] The embodiments of the present invention are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that various variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A moisture-crosslinkable ethylene-vinyl acetate composition, comprising the following components and corresponding parts by weight: 65-80 parts of ethylene-vinyl acetate polymer, 5-10 parts of vinyl copolymer, 9-15 parts of silane oligomers Organosilanes 5.4-9.4 parts, Peroxide initiator 0.2-0.4 parts, Antioxidant 0.2-0.4 parts; The vinyl copolymer is an ethylene-acrylic acid copolymer resin. The silane oligomer is an acyloxysilane oligomer. The organosilane is an allyl macrocyclic polyalkoxysilane. The peroxide initiator is di-tert-butylperoxide isopropylbenzene. The antioxidant is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

2. The method for preparing the moisture-crosslinkable ethylene-vinyl acetate composition according to claim 1 is carried out according to the following steps: (1) Add ethylene-vinyl acetate polymer, ethylene-acrylic acid copolymer resin, acyloxysilane oligomer, allyl macrocyclic polyalkoxysilane, and antioxidant to the reactor with a heating temperature of 130℃~158℃ in sequence, and mix thoroughly under vacuum for 60min~80min. (2) After mixing evenly, heat the reactor to 179-188℃, add di-tert-butyl peroxide isopropylbenzene, and carry out a stirring crosslinking grafting reaction; and evacuate the reactor, keeping the vacuum pressure at 0.7 MPa to 0.9 MPa, and the reaction time is 5-10 minutes; to obtain a moisture-crosslinkable ethylene-vinyl acetate composition.

3. The method of making a moisture-crosslinkable ethylene-vinyl acetate composition according to claim 2, characterized in that: The composition after the reaction and grafting in step (2) is vacuum sealed for later use.

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