JP2003306650A - Adhesive tape - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain an adhesive tape which is suitable for use in a limited space and has a reduced smell. <P>SOLUTION: The adhesive tape comprises an acrylic adhesive layer having ≤150 ppm volatile content for ≥6 minute retention time detected by a measurement condition A defined in the text of the specification and preferably ≤800 ppm volatile content for ≥6 minute retention time detected by a measurement condition B defined by the text of the specification. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adhesive tape and an adhesive method preferably used for adhesive fixing in a closed space such as a vehicle or a house.

[0002]

2. Description of the Related Art Conventionally, double-sided pressure-sensitive adhesive tape has been widely used in vehicles and houses for adhesively fixing members. In recent years, adhesive tapes used in closed spaces such as automobiles and houses are strongly required to have low odor.

It is generally considered that the cause of odor is the residual solvent, residual monomer, tackifying resin or polymerization initiator contained in the material constituting the adhesive tape. JP-A-6-122859 discloses that by polymerizing a monomer having a large molecular weight and a low saturated vapor pressure,
A method for obtaining a pressure-sensitive adhesive having less residual monomer is disclosed. Further, JP-A-2-115291 discloses a pressure-sensitive adhesive using an acrylic polymer obtained by polymerizing a specific acrylic monomer in order to reduce odor.

However, in these methods, a commonly used monomer cannot be used as a main monomer, and it has been difficult to achieve both adhesive physical properties and low odor properties.

Further, Japanese Patent Application Laid-Open No. 8-269139 proposes a method for reducing odor caused by the residual solvent by polymerizing at a temperature not lower than the boiling point of the solvent. However, this method does not consider the odor caused by substances other than the residual monomer.

[0006]

Conventionally, a method for reducing odor by reducing residual monomers and residual solvents has been proposed as described above. However, these methods have been difficult to apply to commonly used pressure-sensitive adhesives. In addition, since the odor-causing substances other than the residual monomer have not been considered so much, the odor could not be reliably reduced.

In view of the above-mentioned conventional state of the art, it is an object of the present invention to provide a pressure-sensitive adhesive tape and a bonding method which can be used for general pressure-sensitive adhesives and have a lower odor.

[0008]

The pressure-sensitive adhesive tape according to the present invention comprises an acrylic pressure-sensitive adhesive layer having a volatile component content of 150 ppm or less with a retention time of 6 minutes or longer detected by the following measurement condition A. Characterize.

Measurement condition A: The amount of volatile components released when the weighed adhesive tape was heated at 90 ° C. for 30 minutes using a thermal desorption device (Perkin Elmer ATD-400) was measured by a GC-MS device. (Made by JEOL Ltd., Automas
sII-15). That is, the volatile components obtained by heating the adhesive tape enclosed in the sample tube at 90 ° C. for 30 minutes are collected and concentrated in a trap tube incorporated in the thermal desorption device, and then the trap tube is heated at 280 ° C. It was heated for 10 minutes and introduced into GC-MS.
For GC-MS measurement, non-polar capillary column (Agilent Technology)
HP-1 made by the company), 0.32 mm × 60 m ×
0.25 μm) and the temperature of the column is maintained at 40 ° C. for 5 minutes, then the temperature is raised to 100 ° C. at a heating rate of 5 ° C./min, and then 320 ° C. at a heating rate of 10 ° C./min. After the temperature was raised to 0 ° C, the temperature was maintained at 320 ° C. The MS measurement range was 30 to 400 amu, the He flow rate was 1.5 ml / min, the ionization voltage was 70 eV, the ion source was 230 ° C., and the interface was 250 ° C. The amount of the volatile component is calculated as the concentration obtained by converting the peak area obtained above into a weight based on an absolute calibration curve using toluene as a standard.

Further, in a particular aspect of the present invention, not only is the amount of volatile components detected under measurement condition A for a retention time of 6 minutes or longer 150 ppm or less,
The amount of volatile components with a retention time of 6 minutes or more detected by
An adhesive tape is composed of an acrylic adhesive layer having a concentration of 00 ppm or less.

Measurement condition B: Using a thermal desorption device (ATD-400 manufactured by Perkin Elmer Co., Ltd.), adhesive tape 120
The volatile components released when heated at ℃ for 30 minutes
-MS device (manufactured by JEOL Ltd., AutomassII-1)
5) was used. Other than the heating conditions for the adhesive tape,
It is the same as the measurement condition A.

In another particular aspect of the present invention, the amount of residual polymerization initiator detected under the above measurement conditions A is set to 30 ppm or less, whereby odor due to the residual polymerization initiator is reduced.

Further, in still another specific aspect of the present invention, the total amount of the residual acrylic pressure-sensitive adhesive-constituting monomers detected by the measurement condition A is 50 ppm or less,
As a result, the odor caused by the acrylic pressure-sensitive adhesive constituent monomer can be reduced.

The pressure-sensitive adhesive tape according to the present invention may be composed only of the above-mentioned acrylic pressure-sensitive adhesive layer, or may be one in which the above-mentioned pressure-sensitive adhesive layer is laminated on both sides of a support.

Further, the bonding method according to the present invention is characterized in that the adherends are bonded to each other by using the adhesive tape constructed according to the present invention. Therefore, it is possible to obtain an adhesive structure in which generation of odor due to the adhesive tape is unlikely to occur.

In a particular aspect of the bonding method according to the present invention, a member housed in an airtight space is used as the adherend, and is therefore caused by a bonded structure in the airtight space such as a vehicle. The odor can be effectively reduced.

The present invention will be described in detail below. In the present invention, the pressure-sensitive adhesive layer for forming the pressure-sensitive adhesive tape is an acrylic pressure-sensitive adhesive layer, and the acrylic pressure-sensitive adhesive layer contains an acrylic polymer as a main component.

The acrylic polymer is a homopolymer of (meth) acrylic acid ester monomer, or (meth)
It is composed of a copolymer of an acrylic acid ester monomer and a vinyl monomer for modification which is copolymerizable therewith.

The (meth) acrylic acid ester monomer may be a primary or secondary alkyl group having 4 to 12 carbon atoms.
An ester of a primary alcohol and acrylic acid or methacrylic acid is preferably used. Such an (meth) acrylic acid ester monomer has an amount of 70 to 99.9 in the monomer composition when the acrylic polymer is the above copolymer.
It is desirable to occupy weight%.

The above-mentioned modified vinyl monomer is used for increasing the cohesive force of the acrylic polymer, has a high glass transition point Tg of itself, and has a high glass transition point T of the polymer molecule.
Those that increase g and those that contribute to the formation of a network structure between polymers by a crosslinking reaction between a functional group contained in the molecule and an external crosslinking agent are appropriately used alone or in combination.

Specifically, examples of the modified vinyl monomer having a high glass transition point Tg include styrene, acrylonitrile, and methyl methacrylate, and examples of the functional group-containing monomer include carboxyl groups such as acrylic acid, methacrylic acid, and crotonic acid. Group-containing monomers; 2-hydroxyethyl (meth) acrylate, hydroxyl group-containing monomers such as n-methylol acrylamide; epoxy group-containing monomers such as glycidyl acrylate and allyl glycidyl ether. The modified vinyl monomer having a high glass transition point Tg is preferably 30% by weight or less in the monomer composition in order to reduce odor, and the functional group-containing monomer is 0.01 to 10% by weight in the monomer composition.
Preferably, it is desirable that the content is in the range of 0.05 to 5% by weight.

The above-mentioned acrylic polymer can be obtained by polymerizing the (meth) acrylic acid ester monomer or a mixture of the (meth) acrylic acid ester monomer and the modified vinyl monomer copolymerizable therewith. The method of copolymerization is mentioned. The polymerization method is not particularly limited, and known polymerization methods such as solution polymerization (boiling point polymerization, polymerization below boiling point), emulsion polymerization, suspension polymerization, and bulk polymerization can be used. It is preferable that the amount of the high-boiling unreacted monomer remaining in the reaction liquid after the polymerization is small, and it is preferable to perform an operation of removing the unreacted monomer as needed during or after the polymerization.

The polymerization initiator used may be a peroxide type polymerization initiator, an azo type polymerization initiator or the like. Peroxides such as peroxycarbonates, ketone peroxides, peroxyketals, hydroperoxides, dialkyl peroxides, diacyl peroxides, peroxyesters (lauroyl peroxide, benzoyl peroxide) and other organic peroxides. Is mentioned.

As the azo polymerization initiator, 2,
2'-azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), dimethyl 2,2'-azobisisobutyrate, etc. Azo compounds and the like.

The above-mentioned polymerization initiator is selected according to the polymerization temperature, and one kind or two or more kinds may be used. The molecular weight when the polymerization initiator becomes a radical is 30-
A polymerization initiator having 60 or less, or 150 to 300 or more, a 10-hour half-life of 90 ° C. or less, and having no aromatic ring in the molecule is desirable for reducing odor.

Specific means for reducing the residual monomer in the polymerization step, that is, the residual acrylic pressure-sensitive adhesive-constituting monomer is, for example, a method of separating and removing the residual monomer in the reflux solvent at the end of the polymerization, an acrylic monomer or a modified monomer. A method of adding a low-boiling-point scavenger monomer which reacts with a vinyl monomer but is easily removed by volatilization at the final stage of the polymerization, and the like.

As a method of separating and removing the residual monomer at the final stage, a method of replacing the reflux liquid of the polymerization solvent with a fresh solvent can be considered. In addition, in the method of adding the scavenger monomer at the final stage of the polymerization, for example, a scavenger monomer having a relatively low boiling point such as vinyl acetate, vinyl butyl ether, methyl acrylate, and styrene has a polymerization rate of 95%.
As mentioned above, it is conceivable to add the monomer in a molar ratio of not less than the residual monomer at a stage of preferably 98% or more. The scavenger monomer may be removed in the drying step during the production of the adhesive tape.

A method of removing residual monomers from the acrylic polymer after completion of the polymerization can also be adopted. In this case, a method of washing the acrylic polymer with a poor solvent for the acrylic polymer is generally used. Among the poor solvents for the acrylic polymer, those having a low boiling point are preferable, and typical examples thereof include methanol, ethanol, n-hexane and n-heptane.

In the present invention, various additives may be added to the acrylic polymer obtained by using various odor reducing methods as described above, if necessary. Examples of such additives include tackifiers, plasticizers, softeners,
Examples include fillers, pigments and dyes. Examples of the tackifier include rosin-modified phenol resin, coumarone indene resin, disproportionated rosin ester resin, hydrogenated rosin ester resin, terpene phenol resin, petroleum resin and the like.

When the tackifier is mixed, it is desirable to mix it in a proportion of 0.1 to 10% by weight with respect to the acrylic polymer. When the tackiness is imparted and the odor is reduced, the tackifier is added. For the acrylic polymer to be composed,
It is desirable that the tackifier is mixed in a ratio of 1 to 5% by weight.

The solution-polymerized acrylic polymer is usually cross-linked by a cross-linking agent which reacts with a functional group introduced into the polymer, thereby enhancing cohesive force. Examples of the cross-linking agent include isocyanate cross-linking agents, aziridine cross-linking agents, epoxy cross-linking agents, and metal chelate cross-linking agents.

As a method for reducing the odor when producing the pressure-sensitive adhesive tape, a method of increasing the drying temperature to such an extent that the pressure-sensitive adhesive layer does not foam, a method of increasing the residence time in the drying oven, and a negative pressure in the drying oven are used. A setting method, a method of increasing the amount of dry air, and the like are conceivable, and these methods can be appropriately combined and used.

As a method for reducing the odor caused by organic volatile substances during the adhesive storage of the adhesive tape, it is conceivable to heat the inside of the curing chamber and reduce the pressure. As a method for producing a pressure-sensitive adhesive tape, an acrylic polymer solution treated as described above as necessary, a pressure-sensitive adhesive solution prepared by adding an appropriately treated additive as necessary, and cross-linked as necessary. The agents are mixed and stirred to prepare an adhesive. Next, the pressure-sensitive adhesive layer is formed by directly coating the pressure-sensitive adhesive on the support or by coating it on the release process paper. In the case of the former after drying, the adhesive tape can be obtained by winding it as it is into a roll or by winding it after superposing the adhesive layer on the release surface of the release paper. In the latter case, the adhesive tape can be obtained by rolling the adhesive layer after transferring it to the support.

In the case of a double-sided pressure-sensitive adhesive tape in which a pressure-sensitive adhesive layer is formed on both sides of a support, the first pressure-sensitive adhesive layer is usually formed on a release paper whose both sides have been subjected to a release treatment, and the pressure-sensitive adhesive layer is formed. After laminating a support such as a non-woven fabric on the agent layer, the second pressure-sensitive adhesive layer formed on the process paper is transferred to the other surface of the support while peeling the process paper and wound into a roll. It is manufactured by the method.

The support is not particularly limited,
Sheets made of paper, non-woven fabric, polyester, polyolefin, polyurethane, polychloroprene, vinyl chloride resin, acrylic resin and the like can be used as appropriate,
You may use the support which performed the foaming process. Also for these base materials, in order to achieve low odor, it is desirable that they be made of a material that has been purified in advance.

[0036]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be clarified by describing specific examples of the present invention. The present invention is not limited to the examples below. Also,
In the following, "part" means "part by weight".

(Example 1) In a reactor equipped with a thermometer, a stirrer, a condenser and a dropping funnel, 85 parts of n-butyl acrylate, 13 parts of 2-ethylhexyl acrylate, 1 part of acrylic acid, and 2-hydroxyethyl. A monomer mixture consisting of 1 part of methacrylate was dissolved in 80 parts of ethyl acetate to prepare 0.3 parts of lauroyl peroxide as a polymerization initiator.
Parts were used and reacted at boiling point for 10 hours. After cooling the solution thus obtained, methanol is added to 600
Part of the polymer was added to precipitate the polymer, and the supernatant was separated and removed. Further, 300 parts of methanol was added, the supernatant was separated and removed, and then the acrylic polymer was redissolved in toluene to prepare a 50 wt% solution of the acrylic polymer.

An isocyanate crosslinking agent (manufactured by Nippon Polyurethane Company,
An acrylic pressure-sensitive adhesive was prepared by uniformly mixing 1 part of a trade name: Coronate L (55% of active ingredient)).

The above acrylic pressure-sensitive adhesive was applied to one surface of a separator made of a polyethylene terephthalate film having a thickness of 50 μm so that the thickness after drying would be 60 μm, and dried at 100 ° C. for 10 minutes, and then a nonwoven fabric substrate made of rayon was used. It was laminated on both sides of the material to obtain an adhesive tape.

Example 2 In Example 1, after reacting for 10 hours, lauroyl peroxide 0.0
5 parts and 10 parts of vinyl acetate were added and reacted for 10 hours.
The solution thus obtained was cooled to obtain an acrylic polymer solution. After measuring the nonvolatile content of the acrylic polymer solution, a 50 wt% solution of the acrylic polymer was prepared with toluene, and an adhesive tape was produced in the same manner as in Example 1 below.

(Comparative Example 1) An adhesive tape was obtained in the same manner as in Example 1 except that the washing operation with methanol was not carried out and that a 50% solution was prepared by diluting with toluene.

Example 3 An adhesive tape was obtained in the same manner as in Comparative Example 1 except that the drying conditions at the time of producing the adhesive tape were 120 ° C. and 20 minutes.

(Example 4) The adhesive tape of Comparative Example 1 was 40
It was stored for 1 week under the condition of ℃ and 0.1 atm.

Comparative Example 2 An adhesive tape was produced in the same manner as in Example 3 except that benzoyl peroxide was used as the polymerization initiator instead of lauroyl peroxide.

(Evaluation of Examples and Comparative Examples) With respect to each of the pressure-sensitive adhesive tapes obtained as described above, physical properties were measured and odor properties and volatile component amounts were evaluated in the following manner.

Evaluation of physical properties: 180 of the obtained adhesive tape
The peeling force was measured according to JIS Z0237. The results are shown in Table 1 below. Odor: Leave the above adhesive tape in an atmosphere of 23 ° C.,
The odor was sensory-evaluated by the following 5-point method. In the sensory evaluation, each of 10 panelists evaluated the adhesive tape by the 5-point method. The values shown in Table 1 below are evaluations evaluated by the most panelists among the 10 panelists. 5 points: no odor 4 points: almost no odor 3 points: odor present 2 points: slightly odor 1 point: fairly strong odor

Measurement of Amount of Volatile Components The amount of volatile components was evaluated under the measurement conditions A and B described above.

[0048]

[Table 1]

[0049]

The pressure-sensitive adhesive tape according to the present invention has a volatile component amount of 150 pp detected under condition A for a holding time of 6 minutes or more.
Since it is m or less, it is possible to provide an adhesive tape having a low odor compared with the conventional adhesive tape. Therefore, it is possible to provide an adhesive tape that is most suitable for adhesive fixation in a limited space in a vehicle or a house.

Claims (7)

[Claims] 1. The amount of volatile components having a retention time of 6 minutes or more detected by the measurement condition A specified in the specification is 150.
An adhesive tape comprising an acrylic adhesive layer having a ppm or less. 2. The amount of volatile components having a retention time of 6 minutes or more detected by the measurement condition B defined in the specification is 800.
2. An acrylic pressure-sensitive adhesive layer having a content of ppm or less.
Adhesive tape described in. 3. The pressure-sensitive adhesive tape according to claim 1, wherein the residual polymerization initiator amount detected by the measurement condition A is 30 ppm or less. 4. The pressure-sensitive adhesive tape according to claim 1, wherein the total amount of residual acrylic pressure-sensitive adhesive-constituting monomers detected by the measurement condition A is 50 ppm or less. 5. The pressure-sensitive adhesive tape according to claim 1, wherein the pressure-sensitive adhesive layer is laminated on both surfaces of a support. 6. A bonding method, wherein adherends are bonded to each other using the adhesive tape according to any one of claims 1 to 5. 7. The bonding method according to claim 6, wherein the adherend is a member housed in an airtight space.