KR20020035869A - Pressure sensitive adhesives for use with data storage devices - Google Patents

Abstract

The present invention discloses a method of making a cleaner and more clean computer device that uses cleaner PSA for computer device components containing a pressure-sensitive adhesive (PSA). The cleaner PSA comprises at least one hydrogenated styrene-elastomer-styrene block copolymer or hydrogenated styrene-elastomer-styrene-elastomer block copolymer, and at least one adhesive resin. A hydrogenated styrene-ethylene butylene-styrene or styrene-ethylene propylene-styrene block polymer in combination with a specific " clean " adhesive resin is compounded with a liquid coating and covered appropriately on an acceptable substrate. The components thus produced are ideally suited for use in disk drives. The components produced in the manner described are much lower in total agglomerate concentration of the material that is considered industrially harmful compared to most polyacrylate adhesive components of the same design. The present invention also discloses a computer device, preferably a computer data storage device, made by the disclosed method.

Description

[0001] PRESSURE SENSITIVE ADHESIVES FOR USE WITH DATA STORAGE DEVICES [0002]

Computer disk drives are composite assemblages of surface treated alloys, plastics, elastomers and ceramic components containing various lubricants and adhesives. Pressure sensitive adhesives (PSA) are currently used in various applications such as sealants, labels, cushioning materials and the like in computer data storage devices. The use of PSA has been recognized as an effective means of lowering the cost of storage devices. A typical drive may include one or more PSA containing components, e.g., tape, for the purpose of holding the housing of the disk drive together.

Due to the demand for increased storage capacity disk drives, products have been designed that require a high level of adhesive contamination. The performance and capacity of disk drive components has been improved by new disc drive technologies such as reducing the height of the tracks, magnetoresistive head technology and pseudo-contact recording. However, when using this new technology, the damage of the disk drive due to environmental factors becomes easier. Constructing the drive with components that tend to be contaminated or emit gases can cause functional problems, including adhesion / wear problems, and electrical failure problems from thermal asperity.

The cleanliness of PSA materials has been of interest to disk drive technicians. Physical contaminants such as dust particles, epidermal slices, and moisture can affect the lifetime of the drive or the reliability of the device, along with chemical contaminants that may be caused by the materials used in the PSA. In addition, the adhesive material can deposit contaminants on the disk and the read head and can cause read errors or disk failure.

Certain ions and organotins are particularly harmful to the heads and discs. It has been found that even materials containing low levels of chlorine can cause disc corrosion. Organic materials that can cause polymerization are also not allowed even at very low levels. Organic acids, inorganic acids, organic bases or inorganic bases can corrode sensitive layers of the storage disk. Typical types of fine contaminants commonly found in the disk drive industry include organic contaminants that can cause adhesion; Corrosive substances from residual anions (especially chloride and sulfate ions); Gas emissions that may cause adhesion; And air suspended particulates.

Polyacrylate PSA has been widely used as a component of a disk drive. However, only selected portions are available; Overall, I was not satisfied. The chemical byproducts generated from initiators used in the initial polymerization of acrylates are not acceptable in disc drives even at relatively low levels. Solvents and impurities used in the dissolution and coating of the polyacrylate PSA can be a problem if they are not completely dried after the finish adhesive coating. Most polyacrylate pressure sensitive adhesives must be chemically crosslinked to provide the required performance characteristics. However, the chemicals used for crosslinking or chemicals as by-products resulting from crosslinking are at an unacceptable or unacceptable level. The levels of unreacted monomers and impurities in the polyacrylate PSA are known to cause drive failure.

The disk drive industry adopts two methods to minimize the micro pollutants in the environment of the disk drive. The first method employs one of a variety of cleaning methods to remove fine contaminants from the finished disk drive component. Typically, such a cleaning method is water cleaning, solvent cleaning or carbon dioxide cleaning. These cleaning methods all have their advantages and disadvantages. However, no cleaning method can remove all contaminants. Cleaning is a proportional removal process and targets specific contaminants. The higher the initial level of pollutant, the higher the final level of pollutant in the finished product.

A second method used in the disk drive industry is to use components and processes that contain or produce less pollutants. This requires more stringent requirements for component suppliers of the disk drive industry. Specific requirements include low gas emission levels and low ionic contaminant levels. For example, a typical limit for gas emissive material may be 2500 ng / cm ² ; The limit of the anion may be up to 800 ng / cm ² .

Further descriptions of the micro-contaminants of the disk drive industry can be found in Peter Mee et al., Management of Disk Drive Component Microcontamination , IDEMA ^R (InSite), Vol. IX, No. 2 (March / April 1997).

The present invention relates to a computer apparatus. More particularly, the present invention relates to a method of making a computer device, such as a pressure sensitive adhesive and a cleaner data storage device, for use in a computer device.

There has been a difficulty in meeting the requirements of disk drive technicians for polyacrylate adhesives in the adhesive industry. The present invention relates to a method of manufacturing a computer device such that there is a lower level of fine contamination around the disk drive.

A hydrogenated styrene-elastomer-styrene block copolymer or hydrogenated styrene-elastomer-styrene-elastomer block polymer in combination with a particular "clean" or "cleanable" adhesive resin is compounded into a liquid coating, . The components thus produced, such as tapes, labels, encapsulants, etc., are ideally suited for use in disk drives. The components prepared in this manner have a much lower total aggregate concentration that is considered to be industrially harmful compared to most similarly designed polyacrylate adhesive components.

In one aspect, the invention includes an improved method of making a computer device comprising at least one component containing a PSA,

A. at least one hydrogenated styrene-elastomer-styrene block copolymer or hydrogenated styrene-elastomer-styrene-elastomer block copolymer, and

B. applying an improved PSA comprising at least one adhesive resin to the PSA containing component.

In another aspect,

A. at least one hydrogenated styrene-elastomer-styrene block copolymer or hydrogenated styrene-elastomer-styrene-elastomer block copolymer, and

B. A computer device comprising at least one PSA containing component comprising at least one adhesive resin.

&Quot; Block copolymer " means a polymer containing a long chain branch of two or more monomeric units bonded by a chemical valence to alternate with one another in a chain. "Diblock copolymer" is a block copolymer having the general structure of A-B, where A is the long chain branch of the first copolymer and B is the long chain branch of the second copolymer. &Quot; Triblock copolymer " is a block copolymer having the general structure of A-B-A, wherein A is the long chain branch of the first copolymer and B is the long chain branch of the second copolymer.

The " adhesive resin " is a resin having properties of a pressure-sensitive adhesive when the composition is added to a rubber or an elastomer. A " pressure sensitive adhesive " is a permanent, cohesive, tacky (adhesive) solid that forms a bond immediately upon application of pressure to the two materials. In the pressure-sensitive adhesive, " tacky " means a property of firmly adhering to the surface even when the adhesive is contacted under a small pressure. The bond strength will become even greater as the pressure increases, thereby defining the term pressure-reducing. Tackiness is assessed as the force required to separate the adhesive from the adhesive at the interface immediately after being quickly contacted under light load for a short time. Tackiness can be measured using the ASTM D-2979 procedure.

&Quot; Hydrocarbon resin " is a resin having a molecular weight of several hundreds to 6,000 or 8,000 and is obtained or synthesized from basic hydrocarbonaceous materials such as petroleum, coal, tar, turpentine oil, and the like.

An improved computer device is made by manufacturing one or more of the adhesives described below and attaching the adhesive to one or more of the components of the computer device. Preferably, the component is a film, tape, or label used to seal or identify one or more components of a computer device. The computer device is preferably a disk drive or other data storage device.

glue

The adhesive used in the present invention comprises at least about 10% by weight, preferably at least about 40% by weight and up to about 90% by weight, preferably up to about 75% by weight, of a block copolymer, based on the total weight of the adhesive, More preferably at least about 10 weight percent, and preferably at least about 25 weight percent to about 90 weight percent, and preferably no more than about 60 weight percent.

Block copolymer

The compositions of the present invention may include various well known block copolymers, including those described in detail in U.S. Patent Nos. 3,239,478 and 3,917,607, both of which are incorporated herein by reference. Such specific block copolymers typically take the general configuration of ABA or ABAB, wherein each block " A ", which is generally characterized as an end block, is selected from the group consisting of styrene, alpha -methyl-styrene, ≪ RTI ID = 0.0 > mono-alkenyl-allene < / RTI >

An elastomeric " B " block, characteristically defined as an "intermediate block," is prepared by transferring a polymer chain of conjugated diene such as butadiene or isoprene from the end of a previously synthesized end block. Then, by using a sequential monomer addition or coupling agent, the desired block copolymer A-B-A or A-B-A-B is produced. When the block copolymer of A-B-A or A-B-A-B is hydrogenated, a saturated midblock will be produced. These block copolymers, which are prepared through known processes, can be prepared by copolymerizing styrene-butadiene-styrene block copolymer (SBS), styrene-isoprene-styrene block copolymer (SIS), styrene- Styrene-ethylene propylene-styrene (SEPS) and methyl styrene-ethylene propylene-a-methyl styrene. Typical molecular weights of such block copolymers are from about 10,000 to about 500,000 (expressed as number average molecular weight).

Preferably, the block copolymer of the present invention is a hydrogenated block copolymer. Hydrogenation minimizes the number of double or triple bonds in a potential gas-releasing material that can polymerize in a computer device component to produce a gas-releasing material. Such polymerization can interfere with the recording, storing or reading of data in a computer data storage device.

The hydrogenated block copolymers are preferably block copolymers of polystyrene and polydiene (the unsaturated midblock of polybutadiene or polyisoprene is hydrogenated to yield a saturated midblock), which is typically a polybutadiene and a polyisoprene Lt; / RTI > The saturated midblock of the hydrogenated block copolymer has a structure of poly (ethylene-propylene), poly (ethylene-butylene), or both.

More preferably, the block copolymers of the present invention comprise styrene end blocks and hydrogenated butadiene and / or hydrogenated polyisoprene intermediate blocks. Such block copolymers are also described in U.S. Patent Nos. 4,136,699; 4,361,672; 4,460, 364; 4,714,749 and 5,459,193, all of which are incorporated herein by reference, and disclosed in KRATON ^R Thermoplastic Rubbers , published by Shell Chemical Company.

Most preferably, the block copolymer has a terminal block of styrene having a number average molecular weight of 10,000 to 30,000, and the middle block is a block of hydrogenated polyisoprene having a number average molecular weight of about 125,000. Such hydrogenated block copolymers are known as styrene-ethylene-propylene-styrene (SEPS) copolymers. Such block copolymers are available from Shell Chemical Company of the KRATON ^R G trademark.

KRATON ^R G hydrogenated block copolymers have a number average molecular weight (measured by gel permeation chromatography (GPC)) of from about 25,000 to about 300,000. KRATON G polymers from ^R, and most preferably ^R G1650 KRATON, KRATON G1652 ^{R, R} KRATON G1654, KRATON G1657 and KRATON ^{R R} G1730, or combinations thereof. More information about KRATON ^R G polymers is disclosed in Polymer for Adhesives and Sealants KRATON ^R G Polymers available from Shell Chemical Company.

In one aspect of the invention, the block copolymer is a " clean block copolymer ". The clean block copolymer has a combination of not more than 200 ng / cm ² , preferably not more than 100 ng / cm ² , more preferably not more than 50 ng / cm ² as measured by the modified EPA method 300.0 Revision 2.1 (described hereinafter) a bromide, chloride, nitrate, nitrite, phosphate, and sulfate anions, and from about 200 ng / cm ² or less, preferably less than about 100 ng / cm ^2, more preferably ammonium less than about 50 ng / cm ² . In addition, a clean block copolymer in combination with an adhesive resin releases less than 1500 ng / cm ² of gas when measured with a modified IDEMA M11-98 (described below).

In another embodiment of the present invention, the block copolymer is a " cleanable block copolymer ". The cleanable copolymer contains more gas-releasing contaminants and anions than the clean block copolymer, but the gas-releasing contaminants and anions are substantially < RTI ID = 0.0 > As shown in FIG. The removal means may comprise ultra-high temperature drying, spray drying, water washing, solvent washing or CO ₂ cleaning. For practical reasons, a preferred means for ion removal is water rinsing.

Adhesive resin

The adhesive resin of the present invention is a resin that predominantly binds to an elastomeric block or an intermediate block and is substantially non-compatible with the non-elastomeric or terminal block. The resin that binds to the intermediate block is such that when the resin that binds to a particular intermediate block is combined with 100 parts of the middle block of the block copolymer and is cast into solution in toluene, It is compatible with the intermediate block in that it represents a film.

In one aspect of the invention, the tackifier resin useful in the present invention must be " clean ". The " clean adhesive resin " is about 200 ng / cm ² or less, preferably about 100 ng / cm ² or less, more preferably about 50 ng / cm ² or less as measured by Modified EPA Method 300.0 Revision 2.1 ^And less than about 200 ng / cm ² , preferably less than about 100 ng / cm ² , more preferably less than about 50 ng / cm ² , and most preferably less than about 2 ng / cm ² of the combined bromide, chloride, fluoride, nitrate, nitrite, phosphate and sulfate anions. / cm < ² >. In addition, the clean adhesive resin in combination with the block copolymer releases gas at less than 1500 ng / cm ² as measured by modified IDEMA M11-98 (described below).

In another embodiment of the present invention, the adhesive resin is a " cleanable adhesive resin ". The cleanable adhesive resin contains more gas-releasing contaminants and anions than the clean adhesive resin, but the contaminants can be substantially removed through the removal means so that the level of residual contaminants is not greater than the level in the clean adhesive resin . The removal means may comprise ultra-high temperature drying, spray drying, water washing, solvent washing or CO ₂ cleaning. For practical reasons, a preferred means for ion removal is water rinsing.

Examples of adhesive resins that may be useful in the present invention include polyhydric esters or hydrogenated rosin esters of rosin, such as glycerol and pentaerythritol esters of hydrogenated rosin and highly stabilized rosin, synthetic polyterpenes, terpene-olefin copolymers , Terpene-phenol, tall oil rosin, synthetic saturated hydrocarbon resins such as saturated alicyclic hydrocarbon, olefin resin, aromatic containing resin, phenol-aldehyde resin,? -Pinene resin,? -Pinene resin, Terpene-phenolic resins, and copolymers such as 1,3-pentadiene and 2-methyl-2-butene, or mixtures thereof. Other examples of adhesive resins are described in U.S. Patent Nos. 4,361,663 and 4,399,249, both of which are incorporated herein by reference; And U.S. Patent Nos. 4,136,699 and 4,361,672; 4,714,749; And 5,459,193.

A preferred adhesive resin of the present invention is of the type known as " hydrocarbon resin ". For hydrocarbon resins, see Kirk-Othmer, Encyclopedia of Chemical Technology, 2nd Edition, Vol. 11, Interscience, New York, 1966, p. 242). Many of the hydrocarbon resins currently on the market are terpene resins, i.e. (repeated) isoprene (C ₅ H ₈ ) or C ₁₀ H ₁₆ units of polymer. The polymer may be a natural or synthetic material, and isoprene is an olefin copolymerizable with other olefins, so the polymer may be a copolymer (including a terpolymer or the like). Terpene-phenol is also produced.

The aromatic monomers useful for forming the aromatic containing resin composition of the present invention may be prepared from any monomers containing substantial aromatic character and polymerizable unsaturated groups. Typical examples of such aromatic monomers are styrene-based monomers such as styrene,? -Methylstyrene, vinyltoluene, methoxystyrene, tertiary butylstyrene, chlorostyrene and the like; And indene monomers including indene, methyl indene, and other materials. The aliphatic monomers are typically natural and synthetic terpenes containing C ₆ and C ₅ cyclohexyl or cyclopentyl saturated groups which may additionally contain a variety of further substantial aromatic ring substituents.

The aliphatic tackifier resin may be prepared by polymerizing a feed stream containing sufficient aliphatic monomers so that the resulting resin exhibits aliphatic properties. The feed stream can be selected from the group consisting of 1,3-butadiene, cis-1,3-pentadiene, trans-1,3-pentadiene, 2-methyl-1,3-butadiene, Other aliphatic unsaturated monomers such as cyclopentadiene, terpene monomers, terpene phenolic resins and other materials. Mixed aliphatic aromatic resins contain sufficient aromatic monomers and sufficient aliphatic monomers to produce resins having both aliphatic and aromatic properties. Davis " The Chemistry of C ₅ Resins " discuss synthetic C ₅ resin technology. A preferred tackifier is a hydrogenated C ₅ to C ₁₂ resin, preferably a C ₉ resin.

Representative examples of useful aliphatic resins include hydrogenated synthetic C ₉ resins, synthetic branches and unbranched C ₅ resins and mixtures thereof.

Representative examples of aromatic adhesive resins are styrenated terpene resins, styrenated C ₅ resins, or mixtures thereof.

Preferably, the tackifier resin is derived by polymerization and hydrogenation of the pure monomeric hydrocarbon feedstock (the hydrocarbon monomers have a carbon number of about 5 or about 9). Such hydrocarbon resins are low molecular weight nonpolar resins that are very stable and softly colored and are proposed for use as plastics, adhesives, coatings, sealants and coke. Hydrogenation minimizes the presence of double or triple bonds in potential gas-releasing materials capable of producing gas-releasing materials that polymerize in the computer device components. Such polymerization can interfere with the recording, storing or reading of computer data storage devices.

More preferably, the adhesive resin of the present invention is a low molecular weight non-polar hydrocarbon resin sold under the REGALREZ ^R from (Hercules Incorporated) Hercules, Inc.. Most preferably, the tackifying resin is at least one REGALREZ ^R 1018, REGALREZ ^R 1085, REGALREZ ^R 1094, and REGALREZ ^R 1126.

Optional ingredient

The PSA of the present invention may optionally comprise other components known in the art. These components may include plasticizing oils, resin modifiers, and antioxidants.

&Quot; Plasticizing oil ", also known as extending oil, is an organic compound that is added to a polymeric polymer to facilitate processing by internal modification (solvation) of the polymeric molecule and to increase the flexibility and toughness of the final product. The increase in flexibility and toughness of the final product is maintained together by secondary valence bonding, wherein the plasticizing oil replaces some of the plasticized oil to polymer linkage to assist in the movement of the polymer chain fragments. Among the more important plasticizing oils are nonvolatile organic liquids and low melting solids (e.g., phthalates, adipates and sebacate esters, polyols such as ethylene glycol and its derivatives, tricresyl phosphate, castor oil, etc.).

These optional components tend to be " dirty " in that they contain undesirable ions and / or cause gas release from the PSA. In particular, antioxidants may be harmful if released into the disk drive system. Thus, the presently preferred embodiment of the present invention does not contain such an optional component. However, the present invention contemplates that the PSA containing such components is less than about 200 ng / cm ² , preferably less than about 100 ng / cm ² , more preferably less than about 100 ng / cm ² , as measured through modified EPA Method 300.0 Revision 2.1 Advantageously a combination of bromide and less than about 50 ng / cm ^2, chloride, fluoride, nitrate, nitrite, phosphate, and sulfate anions, and from about 200 ng / cm ² or less, preferably less than ² from about 100 ng / cm, More preferably less than about 50 ng / cm < ² > of ammonium. In addition, such PSAs release less than 1500 ng / cm < ² > of gas when measured through the modified IDEMA M11-98 (described below).

How to form PSA

PSA compositions of hydrogenated block copolymers and adhesive resins can be formed through techniques well known in the art, such as those described in U.S. Patent No. 4,361,672. Examples of suitable methods of forming PSA include (i) blending in a high temperature dual roll mill; (Ii) mixing until the melting and melting components of the block copolymer and the pressure-sensitive adhesive resin become uniform; (Iii) other methods used in the plastics and elastomer industries, such as high shear strength mixing, biaxial screw extrusion or tandem extrusion techniques; And (iv) dissolving a suitable organic mixture such as toluene and heptane and forming a homogeneous solution, which is then coated onto the substrate before the solvent evaporates.

High temperature melt blending (methods (i) to (iii) above) are not preferred embodiments of the present invention. In the process, heating can decompose the components of the PSA, thereby producing more material that is potentially capable of releasing gas from the PSA. However, the present invention contemplates the use of a process wherein the resulting PSA releases less than 1500 ng / cm ² of gas when measured with a modified IDEMA M11-98 (described hereinafter).

Preferably, the PSA of the present invention is formed by dissolving the mixture in a suitable organic solvent to form a homogeneous solution and coating the solution onto the components of the computer apparatus before the solvent evaporates. Preferably, such a solution is present in an amount of less than about 10% by weight, more preferably less than about 20% by weight, most preferably from about 30% by weight to preferably about 80% by weight, By weight, up to about 60% by weight, most preferably up to about 50% by weight solids.

Suitable organic solvents should be inert to the block copolymer and the adhesive resin. In addition, the organic solvent should be selected so that substantially all of the solvent can be evaporated from the PSA. &Quot; Substantially all of the solvent " refers to the solvent being removed such that the residual level of the solvent is less than about 5% of the total gas released material in accordance with the modified IDEMA M11-98 (described below). Preferred organic solvents are toluene, cyclohexane and heptane, more preferably toluene.

The solvent may be evaporated from the PSA via any technique known in the art such as vacuum drying or preferably exposing to hot air in a drying oven. The temperature of the hot air should be kept below the natural ignition point of the solvent. The proper drying conditions depend on the substrate to which the PSA is applied and the processing time used for drying. For example, when using a substrate comprising an S type polyester film (available from DuPont), the preferred hot air temperature for evaporating toluene from the PSA of the present invention is about 250 < RTI ID = 0.0 > Deg.] F to about 350 [deg.] F, more preferably about 325 [deg.] F to about 350 [deg.] F for a drying time of 3 minutes. The actual upper limit of the drying time is determined in consideration of the usable apparatus and the desired production speed.

A feature of the PSA of the present invention is that the PSA is less than 1500 ng / cm ² , preferably less than 700 ng / cm ² , more preferably less than 50 ng / cm ² as measured by modified IDEMA M11-98 Gas is released.

Another feature of the PSA of the present invention is that the PSA is less than about 200 ng / cm < ² > of the combined bromide, chloride, fluoride, nitrate, nitrite, Phosphate and sulfate anions, and ammonium at less than about 200 ng / cm ² .

The following specific embodiments will more accurately describe the present invention and will teach the improvements and advantages realized by the present invention as well as the currently preferred process. These embodiments are provided to illustrate the objects of the present invention and should not be construed as limiting the scope of the present invention.

Example 1 - Measurement of gas releasing substance

The gaseous effluent was subjected to the IDEMA M11-98 Dynamic (5/28/99 DRAFT) Headspace Outgas Procedure (referred to herein as the reference) according to the method detailed below or modified (IDEMA M11-98) .

Permanent and consumable devices (Section 2) shall be constructed from: (a) a 303 type stainless steel cylindrical chamber with approximate internal dimensions of approximately 1.25 in. (Depth) x 2.25 in. (Diameter); (b) Supelco 16823-0048 Westpelco, Belle Font, West Pelco Park) Stainless steel thermal desorption tubes (packed with the following absorbent: A layer = 100 mmg Tenax TA, B layer = 250 mmg Carbotrap B); c) Hewlett-Packard Hewlett-Packard: Hewlett-Packard Chemical Analysis Group, Wilmington Center, Wilmington 19808-1610 USA) Gas chromatograph / 5973 mass spectrometer; (d) Perkin Elmer (06859-0019, ATD-400 automated thermal desorption unit; (e) Reztek (Reztech Corporation, Belle Font Banners Circle 110, Pennsylvania, USA) XTI (registered trademark of Reztech Corporation) gas chromatograph Graph column, Reztek pn # 122 Hexadecane (Fisher Scientific, Fisher Scientific, pn # 03035, 711, Pittsburgh, Fowdes Avenue, Pittsburgh, PA 15219-4785, USA) in dichloromethane, used as an external standard for semi-quantitation, .

Sample collection and analysis (section 3) is performed as follows. The heat desorption tube was set at 320 DEG C for 8 minutes. A desorption tube is installed and a sample is placed in the sample gas release chamber. The flow rate of the sample chamber is set to about 50 ml / min using 99.99% nitrogen gas. The gas discharge chamber is continuously heated at a temperature of 85 캜. The desorber is programmed to desorb at 320 ° C for 8 minutes at a rate of 50 ml / min. The cold trap was set at -30 ° C and then desorbed at 350 ° C with a waiting time of 8 minutes and the valve and line temperature set to 200 ° C. The outlet section is set at 54 ml / min. The sample split ratio is about 49: 1. The gas chromatograph flow rate is about 1 ml / min.

Semi-quantification was achieved by injecting 5 μl of a 200 ng / μl solution of n-hexadecane in dichloromethane through a serial inlet into a heated sample chamber and releasing the gas onto a thermally desorbed tube reset at 85 ° C for 185 minutes do. The response coefficient is calculated by averaging the peak area of the total ion chromatogram repeated 6 or more times.

The total ion count at the peak of the target compound or compounds is divided by the external standard response factor and multiplied by 1,000 ng to calculate the amount of the target compound or compounds. The total gas release of the sample is determined by integrating a maximum of 20 +/- 2 peaks. The final result is expressed in ng / cm < ² > and the sample area is determined by summing both areas of the film sample.

Example 2 - Measurement of ion

Ion analysis is carried out on samples extracted by ion chromatography according to EPA Method 300.0 Rev. 2.1 (August 1993) (modified herein), which is modified in Table 1. In this method, a small volume 2 to 3 ml) is introduced into ion chromatography. Critical ions are separated and measured using a system of guard columns, analytical columns, suppressor devices and conductivity detectors.

Specific details of the method are as follows. The ion chromatograph system consists of a Dionex DX500 ion chromatograph equipped with an ED40 electrochemical detector, a GP40 gradient pump and an AS40 autosampler, all available from Dionex Corporation. Samples are extracted by cutting a 100 cm ² surface area of the sample (one side) using a 4.4 cm x 22.6 cm template. The liner is removed from the sample and the adhesive is placed on a clean 200 ml Pyrex beaker with no adhesive on the part of the strip. Add 100 ml of 18.3 MΩ-cm deionized water to the beaker and cover the beaker with an 80 × 40 (No. 3140) Pyrex cap. The beaker is placed in a water bath and heated to a temperature of 80 ° C ± 5 ° C. The temperature of the sample is maintained at 80 占 폚 for 1 hour. After 1 hour, the beaker is taken out from the water bath and cooled to room temperature. Thereby, water having extracted ions is prepared for analysis.

Improvements to Modification Method 2.1 of EPA Method 300.0 Method section Cation analysis Anion analysis 6.2.1-6.2.2.2 Column: Dionex CG12A 4 mm Dionex CS12A 4 mm Column: Dionex ATC-1 Dionex AG11 4 mm Dionex AS11 4 mm 6.2.3 Surfer: Dionex CSRS II 4 mm Suppressor: Dionex ASRS Ultra 4 mm 6.2.4 ED40 electrochemical detector DS3 conductivity cell detection stabilizer DE40 electrochemical detector DS3 conductivity battery detection stabilizer 6.3 Software: Peaknet 4.3 Software: PeakNet 4.3 GP40 / ED40 Time Set Performed Settings: Isocratic analysis Component Analysis: Initial to 9.50 min 90% A and 10% B 9.50 min Injection Sample 13.00 min 100% B 25.00 min 65% B and 35% C Sample Loop Volume: 100 μl 100 μl SRS Current: 300mA 300mA Pump Speed: 1 ml / min 2 ml / min 4 point measurement quadratic curve correlation coefficient > 0.9999 for all ions > 0.9999 for all ions Running time: 11 minutes 25 minutes 7.3 Solvent: 30 mN H ₂ SO ₄ Solvent: A: deionized water (18.3 M? -Cm) B: 5 mM NaOHC: 100 mM NaOH

Example 3 - Formulation

The following is an example of a tape component comprising the PSA of the present invention. Examples A to D are prepared with hydrogenated triblock S-EB-S copolymers, hydrogenated S-EP-S-EP block copolymers, hydrocarbon resins and optional resin modifiers for bonding. The formulations of Examples A to D are shown in Table 2 below.

Examples of PSA formulations ingredient function A B C D (part) (part) (part) (part) KRATON ^R G 1650 ¹ Block polymer 2.91 2.41 4.69 7.87 KRATON ^R G 1657 ¹ Block polymer 4.20 6.73 3.04 3.15 KRATON ^R G 1730 ¹ Block polymer 38.91 40.15 39.83 39.45 REGALREZ ^R 1085 ² Adhesive resin 39.22 42.11 42.73 41.82 REGALREZ ^R 1018 ² Adhesive resin 7.75 5.91 4.74 4.65 MOR-ESTER ^R 49007 ³ Adhesion modifier 7.01 2.70 4.97 3.07 1. KRATON ^R is a block copolymer trademark of Shell Chemical Company: G-1650 is S-EB-S containing 30% styrene and 0% diblock; G-1657 is S-EB-S containing 13% styrene and 29% diblock; G-1730 is S-EP-S-EP containing 22% styrene and 0% diblock. REGALREZ ^R is a trademark of the hydrocarbon resin of Hercules Inc. 3. MOR-ESTER ^R is a trademark of Morton International Inc. semi-rigid adhesive polyester resin designed as an adhesive resin.

The adhesive solutions of Samples A to D were prepared by dissolving the components in toluene to obtain a concentration of about 40% solids. A reverse roll sheeting device is used to coat the solution at 0.0025 " thickness on each side of a 0.0005 " thick S type polyester film available from DuPont. Each coated side of the film is dried by passing it through a 12-ft, 2-band drying oven at a rate of 4 ft / min. The resulting dry adhesive layer is 0.001 " thick. The temperature of the first zone of the oven is 325 [deg.] F and the temperature of the second zone of the second coated surface of the oven is 350 [deg.] F.

The Hewlett-Packard 6890 gas chromatograph / 5973 mass spectrometer used in accordance with the modified IDEMA M11-98 is used to measure the gas emissions of Examples A to D. The gas emission measurement results are shown in Table 3 together with the typical ionic levels of Formulas A to D below. The total ion results shown in Table 3 are the average of several measurements and are reported according to the accuracy and precision of the test method tolerances.

(Using Dionex DX500 ion chromatograph equipped with ED40 electrochemical detector and used according to EPA method 300.0 Rev. 2.1 for total ion measurement of adhesive formulations)

Gas emission and ion data Example Gas release (ng / cm ² ) Total amount of ions (ng / cm ² ) A 30 <100 B 16 <100 C 28 <100 D 21 <100

The results shown in Table 3, PSA composition of the present invention (Examples A to D) are prepared emit significantly lower quantities of material than a typical industrial limit of 1500 ng / cm ² gas and to actually release the gas to less than 50 ng / cm ² Can be achieved. PSA prepared according to the present invention releases substantially less material than the most recent polyacrylate PSA prepared under similar conditions.

The total ion content reported in Table 3 demonstrates that the PSA of the present invention can easily be produced to meet or exceed the industry standard of 800 ng / cm ² and indeed to have a total ion content of less than about 100 ng / cm ² .

Claims (15)

A. at least one hydrogenated styrene-elastomer-styrene block copolymer or hydrogenated styrene-elastomer-styrene-elastomer block copolymer, and B. An improved method of making a computerized device comprising applying to the PSA containing component an improved pressure sensitive adhesive (PSA) comprising at least one adhesive resin, wherein the improved pressure sensitive adhesive comprises at least one PSA containing component. The method according to claim 1, Wherein the PSA emits less than about 1500 ng / cm &lt; ² &gt; of gas as measured with the modified IDEMA M11-98. The method according to claim 1, Wherein the PSA emits less than about 700 ng / cm &lt; ² &gt; of gas when measured with a modified IDEMA M11-98. The method according to claim 1, Wherein the PSA releases gas at less than about 50 ng / cm &lt; ² &gt; when measured with a modified IDEMA M11-98. 3. The method of claim 2, PSA is modified EPA method modifying the 2.1 about 200 ng / cm ² less than the combined bromide as measured by the 300.0, chloride, fluoride, nitrate, nitrite, phosphate, and sulfate anions, and from about 200 ng / cm ² less than Lt; RTI ID = 0.0 &gt; of ammonium. &Lt; / RTI &gt; The method according to claim 1, PSA is modified EPA method combined bromide crystal of 300.0 way than about 100 ng / cm ² as measured at 2.1, chloride, fluoride, nitrate, nitrite, phosphate, and sulfate anions, and less than about 100 ng / cm ² Lt; RTI ID = 0.0 &gt; of ammonium. &Lt; / RTI &gt; The method according to claim 1, PSA is revised EPA method modifying the 2.1 about 50 ng / cm ² less than the combined bromide as measured by the 300.0, chloride, fluoride, nitrate, nitrite, phosphate, and sulfate anions, and less than about 50 ng / cm ² Lt; RTI ID = 0.0 &gt; of ammonium. &Lt; / RTI &gt; The method according to claim 1, (Ethylene-propylene) and poly (ethylene-butylene) structures of an elastomeric component of a hydrogenated styrene-elastomer-styrene block copolymer or hydrogenated styrene-elastomer-styrene- Gt; The method according to claim 1, An improved preparation of a computerized device wherein the elastomeric component of a hydrogenated styrene-elastomer-styrene block copolymer or a hydrogenated styrene-elastomer-styrene-elastomer block copolymer is prepared by (i) polymerization of isoprene or (ii) 1,3-butadiene Way. The method according to claim 1, Wherein the PSA comprises from about 5 to about 95 weight percent block copolymer and from about 5 to about 95 weight percent adhesive resin based on the weight of PSA. The method according to claim 1, Wherein the adhesive resin is a hydrocarbon resin. 12. The method of claim 11, Wherein the adhesive resin is hydrogenated. The method according to claim 1, Wherein the computer device is a data storage device. A. at least one hydrogenated styrene-elastomer-styrene block copolymer or hydrogenated styrene-elastomer-styrene-elastomer block copolymer, and B. A computer device comprising one or more components containing a PSA comprising at least one adhesive resin. A. at least one hydrogenated styrene-elastomer-styrene block copolymer or hydrogenated styrene-elastomer-styrene-elastomer block copolymer, and B. A computer data storage device comprising one or more components containing a PSA comprising at least one adhesive resin.