JP5023336B2 - Fingerprint collection sheet - Google Patents

Description

  The present invention relates to a fingerprint collecting sheet used when collecting fingerprints.

Conventionally, as a fingerprint collecting sheet used when collecting a fingerprint, a sheet using a gel sheet has been proposed (see, for example, Patent Document 1).
According to the following Patent Document 1, by configuring a fingerprint collecting sheet using a gel sheet having a certain hardness and elasticity, even in the case of a collection object having a large change in the shape of a curved portion or an uneven portion, the gel sheet It is disclosed that fingerprints adhered to the surface along the shape of the curved portion or the uneven portion can be collected in close contact with the surface along the shape of the curved portion or the uneven portion.
JP 2006-333890 A

However, the fingerprint collecting sheet described in Patent Document 1 also has the following problems.
First, the fingerprint collecting sheet described in Patent Document 1 was formed of a very soft material having an Asker C hardness of 3 to 20 (see Patent Document 1: Claim 1). Therefore, if the gel sheet is thinned, it is difficult to maintain the sheet-like form with the gel sheet alone, and the gel sheet is wrinkled during fingerprint collection, or the gel sheet is excessively stretched, and the fingerprint is collected appropriately. There was a risk of being unable to do so.

  Therefore, in order to prevent the occurrence of such wrinkles and to take an accurate fingerprint while paying attention not to excessively stretch the gel sheet, very high technology and careful work are required. It was.

  In the case of the fingerprint collecting sheet described in Patent Document 1, the thickness is set to about 1.5 to 3.0 mm (see Patent Document 1: Claim 1). There is a desire to use a sheet.

  However, since the fingerprint collecting sheet described in Patent Document 1 is formed of an excessively soft material as described above, generation of wrinkles or excessive elongation as described above is likely to occur when the sheet is thinned. Therefore, there is a problem that it is unavoidable that the gel sheet must be designed to be thick, and it is difficult to meet the demand for reducing the sheet thickness to less than about 1 mm, for example.

  Further, in the above-mentioned Patent Document 1, it is disclosed that a suppression sheet that suppresses the expansion of the gel sheet is fixed to the opposite side of the fingerprint collecting surface (Patent Document 1: refer to claim 4). Then, there is a demand to peel off and use this kind of suppression sheet.

  However, since the fingerprint collecting sheet described in Patent Document 1 is formed of an excessively soft material as described above, generation of wrinkles and excessive elongation as described above may occur if the suppression sheet is peeled off. It tends to happen. Therefore, there has been a problem that the suppression sheet has to be used without being peeled off.

  Since these problems are caused by the gel sheet being excessively soft, it is one idea to make the gel sheet hard to some extent. If you just want to harden the gel sheet, if you reduce the oil mixing ratio, the gel sheet Is considered to be stiff.

  Specifically, in the case of the technique described in Patent Document 1, the gel sheet is formed mainly of an addition polymerization thermoplastic block elastic body and paraffinic oil (see Patent Document 1: Claim 3). . Therefore, the gel sheet can be hardened by reducing the blending ratio of the paraffinic oil.

  However, simply lowering the blending ratio of the paraffinic oil tends to decrease the fingerprint collecting performance as the gel sheet becomes harder. Therefore, even if the sheet thickness is reduced to about 1 mm or less, the gel sheet alone can maintain the sheet-like form, and even if the suppression sheet is peeled off, the sheet can be maintained to such an extent that the gel sheet alone can maintain the sheet-like form. If it is hard, there is a problem in that the fingerprint collecting performance is significantly lowered.

  In addition, simply lowering the blending ratio of the paraffinic oil may cause yellowing in the finally obtained gel sheet. If such yellowing occurs, the transparency of the gel sheet is impaired. There was also.

  The present invention has been made to solve the above-mentioned problems, and its purpose is to capture a fingerprint that can maintain a sheet-like form independently even if it is thinned, and does not cause a decrease in fingerprint collecting performance accompanying the thinning. To provide a sheet.

Hereinafter, the configuration employed in the present invention will be described.
The fingerprint collecting sheet according to claim 1 is a fingerprint collecting sheet provided with a gel sheet formed by forming a gel-like resin composition into a sheet shape, the gel-like resin composition comprising a styrene-based thermoplastic elastomer Random polypropylene copolymer 0.1 to 100 parts by weight of hydrocarbon process oil 150 to 250 parts by weight, hydrogenated petroleum resin 5 to 50 parts by weight, ethylene or ethylene α-olefin copolymer content 3 to 30% by weight It mix | blends-10 weight part, It is characterized by the above-mentioned.

  The fingerprint collecting sheet according to claim 2 is the fingerprint collecting sheet according to claim 1, wherein the gel sheet has a sheet thickness of 0.3 to 0.5 mm.

  The fingerprint collecting sheet according to claim 3 is the fingerprint collecting sheet according to claim 1 or 2, wherein the gel sheet has an Asker C hardness of 20 to 50. Features.

  Furthermore, the fingerprint collecting sheet according to claim 4 includes the auxiliary sheet laminated on the gel sheet in the fingerprint collecting sheet according to any one of claims 1 to 3, wherein the auxiliary sheet includes the auxiliary sheet, It has a structure that can be peeled off from the gel sheet, and the gel sheet and the auxiliary sheet can be left stacked, and the auxiliary sheet can be peeled off from the gel sheet, so that fingerprints can be collected with the gel sheet. It is configured.

  In the fingerprint collecting sheet of the present invention configured as described above, among the components constituting the gel resin composition, as the styrene-based thermoplastic elastomer, for example, styrene isoprene styrene block copolymer (SIS), Styrene butadiene styrene block copolymer (SBS), styrene ethylene propylene block copolymer (SEP), styrene ethylene butylene styrene block copolymer (SEBS), styrene ethylene propylene styrene block copolymer (SEPS), styrene ethylene ethylene propylene Examples thereof include a styrene block copolymer (SEEPS). Any one of these may be used alone, or two or more thereof may be blended and used.

  In addition, as the hydrocarbon-based process oil, any of paraffinic, naphthenic, and aromatic types can be used. Any one of these may be used alone, or two or more thereof may be blended and used. In addition to these, any polymer having good compatibility with a polymer (styrene-based thermoplastic elastomer) and excellent in transparency can be used, such as poly α-olefin (PAO), liquid polybutene, and liquid polyisobutylene. Softeners can also be used.

  When the blending ratio of the hydrocarbon process oil is less than 150 parts by weight, the gel sheet tends to be excessively hard, whereas when the blending ratio of the hydrocarbon process oil is more than 250 parts by weight, the gel sheet tends to be excessively soft. Therefore, in any case, the fingerprint collecting performance is degraded.

  Examples of hydrogenated petroleum resins include aliphatic (C5) petroleum resins, aromatic (C9) petroleum resins, copolymer (C5 / C9) petroleum resins, and alicyclic (hydrogenated). And hydrogenated products such as dicyclopentadiene (DCPD) petroleum resins and styrene (styrene-based, substituted styrene-based) petroleum resins.

  When the blending ratio of the hydrogenated petroleum resin is less than 5 parts by weight, the adhesive strength is excessively lowered, and the fingerprint collecting performance is lowered. On the other hand, when the blending ratio of the hydrogenated petroleum resin exceeds 50 parts by weight, the tackiness becomes excessively high, so that there is a tendency that problems such as poor workability when performing fingerprint collecting work are likely to be caused.

  The random polypropylene copolymer having an ethylene or ethylene α-olefin copolymer content of 3 to 30% by weight is a random copolymer of propylene and a small amount of ethylene or ethylene α-olefin. Here, examples of the α-olefin include 1-butene, 3-methyl 1-butene, 3-methyl-1-pentene, 4-methyl-1-pentene, and 1-octene.

  When the blending ratio of the random polypropylene copolymer is less than 0.1 parts by weight, the effect of suppressing yellowing that occurs in the gel sheet becomes low. On the other hand, when the blending ratio of the random polypropylene copolymer is more than 10 parts by weight, the gel sheet is likely to be hard, which may be a factor of deteriorating the fingerprint collecting performance.

  Therefore, it is important to adjust the blending ratio of these components within the numerical range defined in the present invention. In addition, as long as it does not inhibit the function of each of the above components, as a trace component other than each of the above components, an antioxidant, an ultraviolet absorber, an anti-aging agent, an ozone degradation inhibitor, an antifungal agent, an antifungal agent, An antistatic agent or the like may be contained.

  According to such a fingerprint collecting sheet, it is possible to form a sheet material having such a hardness that it can maintain a sheet-like form alone. Accordingly, wrinkles are not generated on the gel sheet at the time of fingerprint collection, or the gel sheet is not excessively stretched, and fingerprints can be collected more appropriately than conventional products that are excessively soft.

  More specifically, according to the fingerprint collecting sheet of the present invention, for example, even when the sheet thickness is set to 0.3 to 0.5 mm, the sheet thickness is small but the sheet thickness is small. The form can be maintained. Therefore, it is possible to meet the demand for using a sheet thinner than the conventional product.

  Incidentally, in the present invention, the sheet thickness can be less than 0.3 mm, but when the sheet thickness becomes excessively thin, the sheet is not stretched, and as a result, the followability to the unevenness of the surface of the sample to be collected is likely to decrease. Become. In the present invention, the sheet thickness can be more than 0.5 mm. However, when the sheet thickness becomes excessively thick, it is difficult to adjust the pressing force according to the surface of the object to be collected. In addition, when the sheet is pressed against or peeled off from the surface of the object to be collected, deformation due to the thickness of the sheet is likely to occur, and accordingly, accurate fingerprint collection tends to be difficult. Therefore, in order to improve these points as well, it is effective to set the sheet thickness to 0.3 to 0.5 mm.

  In addition, according to the fingerprint collecting sheet of the present invention, for example, a sheet material having a hardness of 20 to 50 in Asker C hardness can be formed. Excessive stretching of the gel sheet can be effectively suppressed.

  Incidentally, in the present invention, the hardness can be less than 20 in terms of Asker C hardness, but when the gel sheet becomes excessively soft, when the sheet is pressed against or peeled off from the surface of the object to be collected, the softness of the sheet Therefore, it is difficult to accurately acquire fingerprints. Moreover, in this invention, although hardness can also be made into over 50 in Asker C hardness, when a gel sheet becomes hard too much, the followable | trackability with respect to the unevenness | corrugation on the surface of a collection object will fall easily. Therefore, in order to improve these points as well, it is effective to set the hardness to 20 to 50 in Asker C hardness.

  Furthermore, even when an auxiliary sheet laminated on the gel sheet is provided, the fingerprint can be collected while the gel sheet and the auxiliary sheet are laminated, and the fingerprint can be obtained with the gel sheet even when the auxiliary sheet is peeled off from the gel sheet. Can be collected.

  Moreover, in spite of the gel sheet having a moderate hardness as compared with the conventional product, since the hydrogenated petroleum resin is blended, the adhesiveness of the sheet surface is high, and good fingerprint collecting performance is exhibited. . Therefore, unlike the case of simply reducing the blending ratio of the oil, the fingerprint collecting performance will not be reduced, and even if the sheet thickness is reduced and the auxiliary sheet is peeled off, there is no problem. Fingerprints can be collected.

  In addition, since a random polypropylene copolymer is blended, the sheet finally obtained is less prone to yellowing despite the fact that it is harder than conventional products, and the transparency of the sheet is also good. It will be a thing. Therefore, unlike the case of simply reducing the blending ratio of oil, the transparency of the gel sheet is not impaired.

  In other words, if the gel sheet is simply hardened, the blending ratio of the oil may be lowered. However, this adversely affects the fingerprint collecting performance and also lowers the transparency of the sheet. On the other hand, in the present invention, the performance of collecting fingerprints is improved by adding a hydrogenated petroleum resin, and the transparency of the sheet is improved by adding a random polypropylene copolymer.

  As a result, in the present invention, it becomes possible to impart an appropriate hardness to the gel sheet without sacrificing fingerprint collection performance and transparency, and it is desired to make the sheet thinner and to use it by peeling off the auxiliary sheet. Was able to respond.

  Further, as a result of adopting such a configuration, the fingerprint collecting sheet of the present invention can be used in a liquid method which is a kind of fingerprint collecting method. That is, in the liquid method, since a chemical solution is used for collecting fingerprints, wettability to the chemical solution and easy handling in a state where the chemical solution is attached or immersed in the chemical solution are required.

  In this respect, the fingerprint collecting sheet of the present invention has better wettability to chemicals than conventional products not containing hydrogenated petroleum resin, and is in an excessively slippery state even when the surface is wet (the surface of the slippery) Therefore, it is easy to handle and appropriate fingerprint collection can be performed.

Next, an embodiment of the present invention will be described with an example.
[Manufacturing method of fingerprint collecting sheet]
For 100 parts by weight of styrene thermoplastic elastomer (in this embodiment, styrene ethylene ethylene propylene styrene block copolymer (SEEPS); styrene content is 30 wt%, viscosity of toluene solution is 5800 mPa · s) 200 parts by weight of paraffinic process oil (with a kinematic viscosity at a temperature of 40 ° C. of about 400 mm 2 / s) and a random polypropylene copolymer having an ethylene or ethylene α-olefin copolymer content of 3 to 30% by weight (MFR of about 20 g / 10 min) Then, 3.4 parts by weight were blended, and these three kinds of raw materials were premixed for 5 minutes with a mixer.

  When the process oil is sufficiently absorbed by the styrenic thermoplastic elastomer, 27 parts by weight of hydrogenated petroleum resin (alicyclic hydrogenated petroleum resin having a softening point of 100 ° C.) is added and premixed for another 3 minutes. did.

  The mixture mixed in the above procedure was kneaded with a heating and mixing mixer at 220 ° C. for 7 minutes to obtain a gel-like resin composition. Then, the gel-like resin composition was formed into a sheet having a thickness of 0.4 mm at 160 ° C., and 50 μm of PET was bonded as an auxiliary sheet (base material) to obtain a target fingerprint collecting sheet (Example) .

In addition, when the hardness of the gel-like resin composition itself was measured with a sheet having a thickness of 12 mm, the Asker C hardness was 30.
For comparison, a conventional product equivalent was prototyped according to the following procedure.

500 parts by weight of the paraffinic process oil was blended with 100 parts by weight of the styrene thermoplastic elastomer, and these two kinds of raw materials were premixed for 8 minutes with a mixer.
The mixture mixed in the above procedure was kneaded with a heating and mixing mixer at 220 ° C. for 7 minutes to obtain a gel-like resin composition. Then, the gel-like resin composition was formed into a sheet having a thickness of 2 mm at 160 ° C., and 50 μm of PET was bonded as an auxiliary sheet (base material) to obtain a comparative fingerprint collecting sheet (Comparative Example).

In addition, when the hardness of the gel-like resin composition itself was measured with a sheet having a thickness of 12 mm, the Asker C hardness was 5.
[Fingerprint collection test]
For the two types of fingerprint collecting sheets (Example, Comparative Example) produced in the above (1), a fingerprint collecting test was carried out according to the following procedure.

  A polypropylene cup (capacity: about 250 cc) was prepared, and the same person grasped the cup almost in the same manner, and fingerprints of the same finger were collected from the same place outside the cup using aluminum powder. Photographs of the collected fingerprints are shown in FIGS. 1 (a) to 1 (d).

  FIG. 1A is a photograph of a fingerprint collected by the fingerprint collecting sheet of the example. As shown in FIG. 1A, when the fingerprint collecting sheet of the example was used, a clear fingerprint could be collected with good reproducibility despite the thin sheet having a thickness of 0.4 mm. Moreover, since the gel sheet has an appropriate tension, the fingerprint could be collected even if the auxiliary sheet (substrate PET) was peeled off and the gel sheet was used alone.

  FIG. 1 (b) to FIG. 1 (d) are photographs of fingerprints collected by the fingerprint collecting sheet of the comparative example. As shown in FIG. 1B, in the case of the fingerprint collecting sheet of the comparative example, the sheet is excessively soft. Therefore, when the gel sheet is pressed against the cup in order from the end with a little force, the gel sheet is gradually distorted. Will be accumulated in the vicinity of the end, which will eventually be pressed against the cup, causing cracks in the collected fingerprint (see the location indicated by the arrow in the figure). It was.

  In addition, the photograph shown in FIG. 1C is a photograph in a case where power is reapplied several times when the fingerprint is collected. If such a sampling operation is performed, the gel sheet will be distorted and moved each time the force is reapplied, or a pattern or crack (such as a point indicated by an arrow in the figure) in the collected fingerprint is different from the fingerprint. See). Therefore, the fingerprint collecting sheet of the comparative example may collect unnecessary lines other than the fingerprint unless care is taken so as not to reapply force during the fingerprint collection. In this respect, since the fingerprint collecting sheet of the example has a tension on the gel sheet, unnecessary lines other than the fingerprint are not collected even if the force is reapplied to some extent during collecting the fingerprint.

  The photograph shown in FIG. 1D is a photograph when the fingerprint is collected by removing the auxiliary sheet from the fingerprint collecting sheet of the comparative example. As shown in FIG. 1D, fingerprint misalignment and wrinkles tend to be more noticeable in the state without the auxiliary sheet than in the state with the auxiliary sheet (see the location indicated by the arrow in the figure).

  Such misalignments and wrinkles are considered to be eliminated if the gel sheet is stretched, so in order to give tension to the gel sheet, I tried collecting fingerprints by stretching and spreading the gel sheet. The image was slightly deformed and shrunk, and the fingerprints were slightly blurred. Therefore, it seems that it is not easy to give the optimum tension to the fingerprint collecting sheet of the comparative example, and even if some tension can be given, individual differences are likely to appear.

[Effect of the embodiment]
As described above, with the fingerprint collecting sheet of the above-described embodiment, a sheet material having a hardness that can maintain the sheet-like form can be formed by itself. For this reason, the gel sheet has an appropriate tension, and the gel sheet is not wrinkled at the time of fingerprint collection, or the gel sheet is not excessively stretched. Therefore, it is possible to collect clear fingerprints that are free from deviations and wrinkles without excessively careful operation compared to excessively soft conventional products.

[Modifications, etc.]
As mentioned above, although embodiment of this invention was described, this invention is not limited to said specific one Embodiment, In addition, it can implement with a various form.

  For example, in the above-described embodiment, specific thermoplastic elastomer, specific process oil, specific hydrogenated petroleum resin, and specific random polypropylene copolymer are exemplified as components blended in the gel resin material. As long as each component has substantially the same physical properties, any material can be adopted without being limited to the above example.

A photograph showing the results of a fingerprint collection test.

Claims (4)

A fingerprint collecting sheet provided with a gel sheet formed by forming a gel resin composition into a sheet,
The gel-like resin composition contains 150 to 250 parts by weight of hydrocarbon-based process oil, 5 to 50 parts by weight of hydrogenated petroleum resin, and ethylene or ethylene α-olefin copolymer with respect to 100 parts by weight of styrene-based thermoplastic elastomer. A fingerprint collecting sheet comprising 0.1 to 10 parts by weight of a random polypropylene copolymer having a rate of 3 to 30% by weight. The sheet for fingerprint collection according to claim 1, wherein the gel sheet has a sheet thickness of 0.3 to 0.5 mm. The sheet for collecting fingerprints according to claim 1 or 2, wherein the gel sheet has an Asker C hardness of 20 to 50. Comprising an auxiliary sheet laminated to the gel sheet,
The auxiliary sheet has a structure that can be peeled off from the gel sheet, the gel sheet and the auxiliary sheet being stacked, and the auxiliary sheet is peeled off from the gel sheet. The fingerprint collecting sheet according to claim 1, wherein the fingerprint collecting sheet is configured to be able to collect fingerprints.