Article and method for manufacturing article

Abstract

To provide an article that comprises a substrate having polyolefin, and an adhesive layer strongly bonded to the substrate.SOLUTION: An article comprises a substrate having polyolefin, and an adhesive layer disposed on the substrate and having polyurethane. At a joint between the substrate and the adhesive layer, an acicular structure comprising polyolefin is formed, projecting from the substrate to the adhesive layer.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an article and a method for making an article. [Background technology]

[0002] Resin substrates containing polyolefins such as polypropylene are widely used industrially, and have the advantages of being lighter and less expensive than metal materials, and being easier to mold and process.

[0003] It is generally known that the surface of a resin substrate is more difficult to wet than that of a metal substrate. This surface's difficulty to wet (hereinafter referred to as "difficulty to wet") can cause defects such as cissing when applying an adhesive. Furthermore, substrates that exhibit poor wettability are generally known to exhibit poor adhesion, which can also be a factor in poor adhesion of adhesives.

[0004] For this reason, studies have been conducted to improve the adhesiveness to adhesives by changing the composition of the substrate, modifying the surface, etc.

[0005] For example, Patent Document 1 describes a method for obtaining a modified polyolefin resin composition having improved properties such as adhesiveness by melt-kneading a polyolefin resin with a radical polymerization initiator, an unsaturated carboxylic acid monomer, and an aromatic vinyl monomer. However, this method requires replacing the conventional resin substrate with a different material, which poses problems in terms of practicality and cost.

[0006] Corona treatment, for example, has been a well-known method for surface modification, but corona treatment has problems such as the need for a large-scale device, which requires a large capital investment, the difficulty in setting optimal conditions, which means that it is not necessarily versatile, and the concern of reduced mechanical strength, etc., because it is a method of cutting molecular chains on the surface of a resin substrate. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-13230 Summary of the Invention [Problem to be solved by the invention]

[0008] The present invention aims to provide an article comprising a substrate containing a polyolefin and an adhesive layer firmly adhered to the substrate, and also aims to provide a method for producing the article. [Means for solving the problem]

[0009] One aspect of the present invention relates to an article comprising a substrate containing a polyolefin and an adhesive layer containing polyurethane disposed on the substrate, wherein needle-like structures containing polyolefin are formed at the joint interface between the substrate and the adhesive layer and protrude from the substrate toward the adhesive layer.

[0010] In one embodiment, the polyolefin may be polyethylene, and in this case, the needle-like structure may include a needle-like structure having a length of 250 nm or more.

[0011] In one embodiment, the polyolefin may be polypropylene, and in this case, the needle-like structure may include a needle-like structure having a length of 20 nm or more.

[0012] In one embodiment, the polyurethane may have an alkanediyl group having 40 or more carbon atoms.

[0013] In one embodiment, the polyurethane may have polyol units (A) and polyisocyanate units (B), where the polyol units (A) may include first polyol units (A-1) having an alkanediyl group having 40 or more carbon atoms.

[0014] In one embodiment, the content of the polyol unit (A) may be 60% by mass or more based on the total amount of the polyurethane.

[0015] In one embodiment, the polyol unit (A) may include a second polyol unit (A-2) having an alkanediyl group having less than 40 carbon atoms.

[0016] In one embodiment, the content of the first polyol units (A-1) may be 90 mass % or more based on the total amount of the polyol units (A).

[0017] In one embodiment, the polyisocyanate units (B) may include a first polyisocyanate unit (B-1) having an aromatic ring.

[0018] Another aspect of the present invention relates to a method for producing an article, comprising: a first step of preparing an unbonded article having a substrate containing a polyolefin and an adhesive layer containing a polyurethane disposed on the substrate; and a second step of heating the bonding surface between the substrate and the adhesive layer of the unbonded article to obtain the article.

[0019] In one embodiment, the article may have needle-like structures with a length of 20 nm or more at the joint surface between the substrate and the adhesive layer, and the unbonded article may not have needle-like structures with a length of 20 nm or more at the joint surface between the substrate and the adhesive layer. [Effects of the Invention]

[0020] According to the present invention, there is provided an article comprising a substrate containing a polyolefin and an adhesive layer firmly adhered to the substrate. Also, according to the present invention, there is provided a method for producing the article. [Brief explanation of the drawings]

[0021] [Figure 1]Figure 1(a) is a diagram showing the observation results of the needle-like structure of Example 1, Figure 1(b) is a diagram showing the observation results of the needle-like structure of Example 2, Figure 1(c) is a diagram showing the observation results of the needle-like structure of Example 3, Figure 1(d) is a diagram showing the observation results of the needle-like structure of Example 4, Figure 1(e) is a diagram showing the observation results of the needle-like structure of Reference Example 1, Figure 1(f) is a diagram showing the observation results of the needle-like structure of Reference Example 2, Figure 1(g) is a diagram showing the observation results of the needle-like structure of Reference Example 3, and Figure 1(h) is a diagram showing the observation results of the needle-like structure of Comparative Example 1. DETAILED DESCRIPTION OF THE INVENTION

[0022] Preferred embodiments of the present invention will be described in detail below.

[0023] (Goods) The article of this embodiment comprises a substrate containing a polyolefin and an adhesive layer containing polyurethane disposed on the substrate. In this embodiment, needle-like structures are formed at the joint surface between the substrate and the adhesive layer, protruding from the substrate toward the adhesive layer, and the needle-like structures contain polyolefin.

[0024] The substrate may have a polyolefin-containing adherend surface on which an adhesive layer is disposed.

[0025] Examples of polyolefins include polyethylene, polypropylene, ethylene propylene rubber, and ethylene propylene diene rubber.

[0026] The substrate and the surface of the substrate on which the adhesive layer is disposed may further contain components other than polyolefin. Examples of other components include fibers (e.g., glass fibers, carbon fibers, basic magnesium sulfate fibers, potassium titanate fibers, aluminum borate fibers, calcium silicate fibers, calcium carbonate fibers, and various metal fibers), inorganic additives (e.g., oxides such as silica, diatomaceous earth, barium ferrite, beryllium oxide, pumice, and pumice balloons; hydroxides such as aluminum hydroxide, magnesium hydroxide, and basic magnesium carbonate; carbonates such as calcium carbonate, magnesium carbonate, dolomite, and dawsonite; sulfates or sulfites such as calcium sulfate, barium sulfate, ammonium sulfate, and calcium sulfite; talc, clay, mica, glass balloons, glass beads, calcium silicate, silicates such as wollastonite, montmorillonite, and bentonite; carbons such as carbon black, graphite, and hollow carbon spheres; molybdenum sulfide, boron fibers, zinc borate, barium metaborate, calcium borate, sodium borate, and magnesium oxysulfate); and elastomers (e.g., α-olefin elastomers and hydrogenated styrene elastomers).

[0027] The adhesive layer is a polyurethane-containing layer disposed on the substrate.

[0028] The adhesive layer may be a layer containing an adhesive composition containing polyurethane.

[0029] The polyurethane has polyol units (A) and polyisocyanate units (B). Here, among the constituent units formed by polymerization of polyol (a) and polyisocyanate (b), the constituent units derived from polyol (a) are polyol units (A), and the constituent units derived from polyisocyanate (b) are polyisocyanate units (B). In other words, the polyurethane may be a polymer of monomers containing polyol (a) and polyisocyanate (b).

[0030] The average number of hydroxyl groups (average functionality) possessed by polyol (a) may be, for example, 1.3 or more, preferably 1.7 or more, more preferably 1.9 or more, and may be, for example, 4 or less, preferably 3 or less, more preferably 2.5 or less, and even more preferably 2.3 or less. The average number of hydroxyl groups (average functionality) possessed by polyol (a) may be less than 2, which may be due to, for example, the inclusion of a monool as an impurity in the diol. It is particularly preferred that polyol (a) be a diol, and it is particularly preferred that polyol unit (A) be a diol unit.

[0031] The average number of isocyanate groups (-NCO) contained in the polyisocyanate (b) (average functionality) may be, for example, 1.3 or more, preferably 1.7 or more, more preferably 1.9 or more, and may be, for example, 4 or less, preferably 3 or less, more preferably 2.5 or less, and even more preferably 2.3 or less. The average number of isocyanate groups contained in the polyisocyanate (b) (average functionality) may be less than 2, which may be due to, for example, the presence of monofunctional isocyanates as impurities in the diisocyanate. It is particularly preferred that the polyisocyanate (b) is a diisocyanate, and it is particularly preferred that the polyisocyanate units (B) are diisocyanate units.

[0032] The polyurethane preferably has an alkanediyl group having a carbon number of at least 40. Use of such a polyurethane makes it easier to form needle-like structures in the production method described below.

[0033] The polyurethane preferably contains, as the polyol unit (A), a first polyol unit (A-1) having an alkanediyl group having 40 or more carbon atoms. That is, the polyol unit (A) preferably contains a first polyol unit (A-1) having an alkanediyl group having 40 or more carbon atoms.

[0034] The first polyol unit (A-1) can be said to be a structural unit derived from a first polyol (a-1) having an alkanediyl group having 40 or more carbon atoms.

[0035] The first polyol unit (A-1) may have a saturated hydrocarbon skeleton such as a polyethylene skeleton, a polypropylene skeleton, a hydrogenated polybutadiene skeleton, a polybutene skeleton, a hydrogenated polyisoprene skeleton, or a hydrogenated polyfarnesene skeleton, and is preferably a polyol unit having oxygen atoms at both ends of the saturated hydrocarbon skeleton.

[0036] The number of carbon atoms in the alkanediyl group (saturated hydrocarbon skeleton) contained in the first polyol unit (A-1) is 40 or more, preferably 50 or more, more preferably 75 or more, and even more preferably 100 or more. The number of carbon atoms in the alkanediyl group (saturated hydrocarbon skeleton) contained in the first polyol unit (A-1) is, for example, 500 or less, preferably 400 or less, more preferably 300 or less, and even more preferably 250 or less.

[0037] The first polyol (a-1) may be, for example, a polyol having a saturated hydrocarbon skeleton such as a polyethylene skeleton, a polypropylene skeleton, a hydrogenated polybutadiene skeleton, a polybutene skeleton, a hydrogenated polyisoprene skeleton, a hydrogenated polyfarnesene skeleton, etc. The first polyol (a-1) is preferably a polyol having hydroxyl groups at both ends of the saturated hydrocarbon skeleton.

[0038] The number of carbon atoms in the saturated hydrocarbon skeleton of the first polyol (a-1) is 40 or more, preferably 50 or more, more preferably 75 or more, and even more preferably 100 or more. The number of carbon atoms in the saturated hydrocarbon skeleton of the first polyol (a-1) is, for example, 500 or less, preferably 400 or less, more preferably 300 or less, and even more preferably 250 or less.

[0039] The average number of hydroxyl groups (average functionality) possessed by the first polyol (a-1) may be, for example, 1.3 or more, preferably 1.7 or more, more preferably 1.9 or more, and may be, for example, 4 or less, preferably 3 or less, more preferably 2.5 or less, and even more preferably 2.3 or less. The average number of hydroxyl groups (average functionality) possessed by the first polyol (a-1) may be less than 2, which may be due to, for example, the presence of a monool impurity in the diol. It is particularly preferred that the first polyol (a-1) is a diol, and it is particularly preferred that the first polyol unit (A-1) is a diol unit.

[0040] The polyurethane may further contain, as the polyol unit (A), a second polyol unit (A-2) having an alkanediyl group having less than 40 carbon atoms. That is, the polyol unit (A) may further contain a second polyol unit (A-2) having an alkanediyl group having less than 40 carbon atoms.

[0041] The second polyol unit (A-2) can be said to be a structural unit derived from a second polyol (a-2) having an alkanediyl group having less than 40 carbon atoms.

[0042] The number of carbon atoms in the alkanediyl group in the second polyol unit (A-2) is less than 40, preferably 30 or less, more preferably 20 or less, and even more preferably 10 or less. The number of carbon atoms in the alkanediyl group in the second polyol unit (A-2) is, for example, 2 or more, preferably 3 or more, and more preferably 4 or more.

[0043] The second polyol (a-2) is preferably, for example, an alkanediol in which two hydroxyl groups are bonded to an alkanediyl group having less than 40 carbon atoms. That is, the second polyol unit (A-2) is preferably an alkanediol unit.

[0044] The number of carbon atoms in the alkanediyl group of the second polyol (a-2) is less than 40, preferably 30 or less, more preferably 20 or less, and even more preferably 10 or less. The number of carbon atoms in the alkanediyl group of the second polyol (a-2) is, for example, 2 or more, preferably 3 or more, and more preferably 4 or more.

[0045] The average number of hydroxyl groups (average functionality) possessed by the second polyol (a-2) may be, for example, 1.3 or more, preferably 1.7 or more, more preferably 1.9 or more, and may be, for example, 4 or less, preferably 3 or less, more preferably 2.5 or less, and even more preferably 2.3 or less. The average number of hydroxyl groups (average functionality) possessed by the second polyol (a-2) may be less than 2, which may be due to, for example, the presence of a monool impurity in the diol. It is particularly preferred that the second polyol (a-2) is a diol, and it is particularly preferred that the second polyol unit (A-2) is a diol unit.

[0046] Specific examples of the second polyol (a-2) include polyether polyols such as polyethylene glycols, polypropylene glycols, and polybutylene glycols; monoglycerides such as caprylic acid monoglyceride, capric acid monoglyceride, lauric acid monoglyceride, stearic acid monoglyceride, and behenic acid monoglyceride; and glycols having a side chain such as 2-methyl-1,3-propanediol and 3-methyl-1,5-pentanediol.

[0047] The proportion of the first polyol units (A-1) in the polyol units (A) (i.e., the content of the first polyol units (A-1) based on the total amount of the polyol units (A)) may be, for example, 70% by mass or more, 80% by mass or more, 90% by mass or more, 95% by mass or more, or even 100% by mass. This tends to facilitate the formation of longer needle-like structures and further improve adhesive strength.

[0048] The proportion of the second polyol units (A-2) in the polyol units (A) (i.e., the content of the second polyol units (A-2) based on the total amount of the polyol units (A)) may be, for example, 30% by mass or less, 20% by mass or less, 10% by mass or less, 5% by mass or less, or even 0% by mass.

[0049] The total proportion of the first polyol units (A-1) and the second polyol units (A-2) in the polyol units (A) (i.e., the total content of the first polyol units (A-1) and the second polyol units (A-2) based on the total amount of the polyol units (A)) may be, for example, 90% by mass or more, preferably 95% by mass or more, more preferably 97% by mass or more, and even more preferably 99% by mass or more, or even 100% by mass. This makes it easier to form longer needle-like structures, and tends to further improve adhesive strength.

[0050] The content of the polyol units (A) may be, for example, 60% by mass or more, preferably 70% by mass or more, more preferably 75% by mass or more, even more preferably 78% by mass or more, still more preferably 80% by mass or more, and even more preferably 82% by mass or more, or may be 84% by mass or more, 86% by mass or more, or 88% by mass or more, based on the total amount of polyurethane. This makes it easier to form longer needle-like structures, and tends to further improve adhesive strength.

[0051] The content of the polyol units (A) may be, for example, 95% by mass or less, 94% by mass or less, 93% by mass or less, 92% by mass or less, 91% by mass or less, or 90% by mass or less, based on the total amount of the polyurethane.

[0052] The polyurethane preferably contains first polyisocyanate units (B-1) having an aromatic ring as the polyisocyanate units (B). That is, the polyisocyanate units (B) preferably contain first polyisocyanate units (B-1) having an aromatic ring.

[0053] The first polyisocyanate unit (B-1) can be said to be a structural unit derived from the first polyisocyanate (b-1) having an aromatic ring.

[0054] The average number of isocyanate groups (-NCO) (average functionality) possessed by the first polyisocyanate (b-1) may be, for example, 1.3 or more, preferably 1.7 or more, more preferably 1.9 or more, and may be, for example, 4 or less, preferably 3 or less, more preferably 2.5 or less, and even more preferably 2.3 or less. The average number of isocyanate groups possessed by the first polyisocyanate (b-1) (average functionality) may be less than 2, which may be due to, for example, the presence of a monofunctional isocyanate impurity in the diisocyanate. It is particularly preferred that the first polyisocyanate (b-1) be a diisocyanate, and it is particularly preferred that the first polyisocyanate unit (B-1) be a diisocyanate unit.

[0055] The aromatic ring contained in the first polyisocyanate unit (B-1) may be, for example, a benzene ring, a naphthalene ring, an anthracene ring, or the like, and is preferably a benzene ring.

[0056] Specific examples of the first polyisocyanate unit (B-1) include diphenylmethane-4,4'-diisocyanate, diphenylmethane-2,4'-diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 1,5-naphthalene diisocyanate, tolidine diisocyanate, xylylene diisocyanate, 1,3-tetramethylxylylene diisocyanate, and 1,4-tetramethylxylylene diisocyanate.

[0057] The polyisocyanate units (B) may further contain, in addition to the first polyisocyanate units (B-1), second polyisocyanate units (B-2) that do not have an aromatic ring.

[0058] The second polyisocyanate unit (B-2) can be said to be a structural unit derived from the second polyisocyanate (b-2) that does not have an aromatic ring.

[0059] The average number of isocyanate groups (-NCO) (average functionality) possessed by the second polyisocyanate (b-2) may be, for example, 1.3 or more, preferably 1.7 or more, more preferably 1.9 or more, and may be, for example, 4 or less, preferably 3 or less, more preferably 2.5 or less, and even more preferably 2.3 or less. The average number of isocyanate groups possessed by the second polyisocyanate (b-2) (average functionality) may be less than 2, which may be due to, for example, the presence of monofunctional isocyanates as impurities in the diisocyanate. It is particularly preferred that the second polyisocyanate (b-2) be a diisocyanate, and it is particularly preferred that the second polyisocyanate units (B-2) be diisocyanate units.

[0060] Specific examples of the second polyisocyanate unit (B-2) include aliphatic diisocyanates such as hexamethylene diisocyanate, isophorone diisocyanate, hydrogenated diphenylmethane-4,4'-diisocyanate, hydrogenated diphenylmethane-2,4'-diisocyanate, hydrogenated xylylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, 2,4,4-trimethylhexamethylene diisocyanate, dimer acid diisocyanate, and norbornene diisocyanate.

[0061] The proportion of the first polyisocyanate units (B-1) in the polyisocyanate units (B) (i.e., the content of the first polyisocyanate units (B-1) based on the total amount of the polyisocyanate units (B)) may be, for example, 70% by mass or more, 80% by mass or more, 90% by mass or more, or 95% by mass or more, or may be 100% by mass.

[0062] The proportion of the second polyisocyanate units (B-2) in the polyisocyanate units (B) (i.e., the content of the second polyisocyanate units (B-2) based on the total amount of the polyisocyanate units (B)) may be, for example, 30% by mass or less, 20% by mass or less, 10% by mass or less, 5% by mass or less, or even 0% by mass.

[0063] The content of the polyisocyanate units (B) may be, for example, 5% by mass or more, 6% by mass or more, 7% by mass or more, 8% by mass or more, 9% by mass or more, or 10% by mass or more, based on the total amount of polyurethane.

[0064] The content of the polyisocyanate units (B) may be, for example, 40% by mass or less, preferably 30% by mass or less, more preferably 25% by mass or less, even more preferably 22% by mass or less, still more preferably 20% by mass or less, and even more preferably 18% by mass or less, and may be 16% by mass or less, 14% by mass or less, or 12% by mass or less, based on the total amount of polyurethane. This makes it easier to form longer needle-like structures, and tends to further improve adhesive strength.

[0065] The polyurethane may further have other structural units in addition to the polyol unit (A) and the polyisocyanate unit (B). Examples of other structural units include polyamine units and polyamino alcohol units.

[0066] The total content of the polyol units (A) and the polyisocyanate units (B) in the polyurethane may be, for example, 90% by mass or more, preferably 95% by mass or more, more preferably 97% by mass or more, and may be 100% by mass, based on the total amount of the polyurethane.

[0067] The number average molecular weight (Mn) of the polyurethane is not particularly limited, but may be, for example, 3000 or more, and preferably 5000 or more. The number average molecular weight (Mn) of the polyurethane may be, for example, 100,000 or less, and is preferably 50,000 or less, more preferably 40,000 or less, even more preferably 30,000 or less, even more preferably 20,000 or less, and still more preferably 10,000 or less.

[0068] The weight average molecular weight (Mw) of the polyurethane is not particularly limited, but may be, for example, 8000 or more, preferably 10000 or more, and more preferably 14000 or more. The weight average molecular weight (Mw) of the polyurethane may be, for example, 95000 or less, preferably 50000 or less, and more preferably 26000 or less.

[0069] In this specification, the number average molecular weight (Mn) and weight average molecular weight (Mw) of polyurethane are values ​​measured by gel permeation chromatography (GPC) under the following conditions. <Measurement of number average molecular weight and weight average molecular weight> The apparatus used was a high-speed GPC system (Tosoh Corporation, HLC-8320GPC), and the columns used were one TSKgel guard column α (6.0 mm I.D. x 4 cm) and two +α-M (7.8 mm I.D. x 30 cm) columns connected in series in the order shown (both columns were manufactured by Tosoh Corporation). Cyclohexanone was used as the mobile phase, and the mobile phase flow rate was 1.0 mL / min. The column temperature was 40 °C, and the detector was an RI detector (polarity (+)). The molecular weight was determined as a polystyrene-equivalent molecular weight. The sample solution was prepared in cyclohexanone to a concentration of 1 mg / mL. The sample injection volume was 100 μL.

[0070] The adhesive layer may be a layer composed of an adhesive composition containing polyurethane.

[0071] The content of polyurethane in the adhesive composition may be, for example, 70% by mass or more, preferably 80% by mass or more, more preferably 90% by mass or more, and may be 95% by mass or more, 97% by mass or more, or 99% by mass or more, or may be 100% by mass, based on the total amount of the adhesive composition.

[0072] The adhesive composition may further contain components other than polyurethane, such as a solvent, a catalyst, an antifoaming agent, a leveling agent, an organic thickener, an antioxidant, a light stabilizer, an adhesion improver, a release agent, a reinforcing material, a softener, a colorant, a flame retardant, an antistatic agent, and a wetting and dispersing agent.

[0073] The thickness of the adhesive layer is not particularly limited and may be, for example, 1 μm or more, preferably 5 μm or more, more preferably 10 μm or more, and may be, for example, 1000 μm or less, preferably 500 μm or less, more preferably 300 μm or less.

[0074] In the article of this embodiment, nano-sized needle-like structures protruding from the substrate toward the adhesive layer are formed on the bonding surface between the substrate and the adhesive layer.

[0075] The needle-like structures are formed when the substrate and the adhesive layer are bonded. That is, the article of the present embodiment may be an article that includes an adhesive layer provided on the adhesion surface of the substrate, and that has needle-like structures protruding from the substrate toward the adhesive layer at the bonding surface between the substrate and the adhesive layer, and that does not have the needle-like structures on the adhesion surface before bonding with the adhesive layer.

[0076] When the polyolefin in the substrate is polyethylene, a relatively long needle-like structure tends to be formed when the substrate and the adhesive layer are bonded. When the polyolefin in the substrate is polyethylene, the length of the needle-like structure is, for example, 250 nm or more, preferably 300 nm or more, more preferably 350 nm or more, and even more preferably 400 nm or more. This tends to further improve the adhesive strength between the substrate and the adhesive layer. When the polyolefin in the substrate is polyethylene, the length of the needle-like structure may be, for example, 2000 nm or less, 1500 nm or less, or 1100 nm or less.

[0077] When the polyolefin in the substrate is polypropylene, a relatively short needle-like structure tends to be formed when the substrate and the adhesive layer are bonded. When the polyolefin in the substrate is polypropylene, the length of the needle-like structure is, for example, 15 nm or more, preferably 20 nm or more, more preferably 25 nm or more, and even more preferably 30 nm or more. This tends to further improve the adhesive strength between the substrate and the adhesive layer. When the polyolefin in the substrate is polypropylene, the length of the needle-like structure may be, for example, 1000 nm or less, 500 nm or less, or 110 nm or less.

[0078] The article of this embodiment may have a plurality of needle-like structures formed on the bonding surface between the substrate and the adhesive layer. When a plurality of needle-like structures is present, it is sufficient that at least some of them satisfy the preferred length range described above, and it is preferable that the majority of them (for example, 60% or more, preferably 80% or more, more preferably 90% or more) satisfy the preferred length range described above.

[0079] The needle-like structure can be observed by the following method, and the length of the needle-like structure can be measured by the following method. <Method for observing needle-like structures> The article of this embodiment is cut into 1 cm square pieces using an ultramicrotome, and the adhesive layer is dyed by exposing it to ruthenium (IV) oxide vapor at atmospheric pressure for 20 minutes. The dyed sample is cooled to -125°C and cut using a cryomicrotome to obtain a thin slice of the sample with a thickness of approximately 100 nm. This thin slice is observed using a transmission electron microscope (JEOL JEM-2100F) to obtain an observation image of the cross section perpendicular to the bonding surface. Observation is performed under conditions of 25°C. In the obtained observation image, the length from the start to the tip of the needle-like structure is measured, and the length of the needle-like structure is determined by calculation based on a scale.

[0080] The article of the present embodiment may further include other members in addition to the substrate and the adhesive layer. For example, the article may have other members bonded to the surface of the adhesive layer opposite to the substrate.

[0081] The article of this embodiment can be produced, for example, by the following method.

[0082] (Production method of article) The method for manufacturing an article of this embodiment includes a first step of preparing an unbonded article having a substrate containing a polyolefin and an adhesive layer containing polyurethane disposed on the substrate, and a second step of heating the bonding surface between the substrate and the adhesive layer of the unbonded article to obtain the article.

[0083] In the method for manufacturing an article of this embodiment, by heating the unbonded article, needle-like structures protruding from the substrate toward the adhesive layer are formed at the bonding surface between the substrate and the adhesive layer. That is, it is preferable that the unbonded article does not have needle-like structures (e.g., needle-like structures with a length of 20 nm or more) at the bonding surface between the substrate and the adhesive layer.

[0084] The first step may be, for example, a step of forming an adhesive layer on the surface of a substrate to be adhered to prepare an unadhesive article.

[0085] The adhesive layer can be formed, for example, by applying a coating liquid containing an adhesive composition and a solvent onto the surface to be adhered of the substrate and drying it.

[0086] The solvent is not particularly limited, and may be, for example, an aromatic hydrocarbon solvent such as toluene, ethylbenzene, trimethylbenzene, or xylene; an aliphatic hydrocarbon solvent such as pentane, hexane, or cyclohexane; a ketone solvent such as acetone, methyl ethyl ketone, methyl isobutyl ketone, or cyclohexanone; an alcohol solvent such as methanol, ethanol, isopropanol, ethylene glycol, diethylene glycol, triethylene glycol, or propylene glycol; a glycol ether solvent such as methyl cellosolve, ethyl cellosolve, butyl cellosolve, methyl diglycol, ethyl diglycol, butyl diglycol, or propylene glycol monomethyl ether; an ester solvent such as ethyl acetate, butyl acetate, or propylene glycol monomethyl ether acetate; an amide solvent such as N,N-dimethylformamide, N,N-diethylformamide, N,N-dimethylacetamide, or N-methylpyrrolidone; an ether solvent such as diethyl ether or tetrahydrofuran; or water. The solvents may be used alone or in combination of two or more.

[0087] The content of the solvent in the coating liquid may be appropriately selected depending on the coating method, the thickness of the adhesive layer, etc. The content of the solvent may be, for example, 1900 parts by mass or less, and preferably 100 to 900 parts by mass, per 100 parts by mass of polyurethane.

[0088] The method for applying the coating liquid is not particularly limited, and may be, for example, an applicator method, a bar coating method, a spin coating method, a spray coating method, a dip coating method, a nozzle coating method, a gravure coating method, a reverse roll coating method, a die coating method, an air doctor coating method, a blade coating method, a rod coating method, a curtain coating method, a knife coating method, a transfer roll coating method, a squeeze coating method, an impregnation coating method, a kiss coating method, a calendar coating method, an extrusion coating method, or the like.

[0089] The drying method after coating is not particularly limited, and examples thereof include a method of evaporating the solvent by heating and / or reducing pressure, etc. The temperature conditions during drying are not particularly limited, and may be, for example, 0 to 200°C, or 50 to 100°C.

[0090] The thickness of the adhesive layer in the unbonded article may be the same as the thickness of the adhesive layer in the article. The thickness of the adhesive layer in the unbonded article may be, for example, 1 μm or more, preferably 5 μm or more, more preferably 10 μm or more. The thickness of the adhesive layer in the unbonded article may be, for example, 1000 μm or less, preferably 500 μm or less, more preferably 300 μm or less.

[0091] The unbonded article may further include other components in addition to the substrate and the adhesive layer. For example, the unbonded article may have other components disposed on the surface of the adhesive layer opposite to the substrate.

[0092] In the second step, the bonding surface between the substrate and the adhesive layer of the unbonded article is heated to form needle-like structures on the bonding surface.

[0093] The heating temperature in the second step may be appropriately changed depending on the type of polyolefin in the substrate. For example, when the polyolefin in the substrate is polyethylene, the heating temperature in the second step may be, for example, 120°C or higher, and from the viewpoint of easily obtaining needle-like structures of a suitable length, it is preferably 130°C or higher, more preferably 135°C or higher, and even more preferably 140°C or higher. Furthermore, when the polyolefin in the substrate is polyethylene, the heating temperature in the second step may be, for example, 300°C or lower, and from the viewpoint of the thermal stability of the substrate, it is preferably 250°C or lower, more preferably 230°C or lower, and even more preferably 200°C or lower.

[0094] When the polyolefin in the substrate is polypropylene, the heating temperature in the second step may be, for example, 120° C. or higher, and from the viewpoint of easily obtaining needle-like structures of a suitable length, is preferably 160° C. or higher, more preferably 170° C. or higher, and even more preferably 180° C. or higher. When the polyolefin in the substrate is polypropylene, the heating temperature in the second step is, for example, 300° C. or lower, and from the viewpoint of the thermal stability of the substrate, is preferably 250° C. or lower, more preferably 230° C. or lower, and even more preferably 200° C. or lower.

[0095] The heating time in the second step may be, for example, 10 seconds or more, and from the viewpoint of easily obtaining needle-like structures of a suitable length, is preferably 60 seconds or more, more preferably 300 seconds or more, and even more preferably 600 seconds or more. The heating time in the second step may be, for example, 3600 seconds or less, and from the viewpoint of production efficiency, is preferably 2700 seconds or less, more preferably 1800 seconds or less, and even more preferably 1200 seconds or less.

[0096] The manufacturing method of this embodiment may further include a third step of bonding another member to the surface of the article obtained in the second step opposite to the adhesive layer.

[0097] Although the preferred embodiments of the present invention have been described above, the present invention is not limited to the above embodiments. [Example]

[0098] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples.

[0099] Example 1 <Production of Polyurethane (1)> A 2 L four-neck separable flask equipped with a stirrer, thermometer, heater, and reflux condenser was charged with 168 g of hydroxyl-terminated hydrogenated polybutadiene, 22 g of diphenylmethane-4,4'-diisocyanate (hereinafter referred to as MDI), 0.15 g of dioctyltin dilaurate, and 1710 g of cyclohexanone at room temperature, and then nitrogen gas was blown in to replace the atmosphere inside the flask. These components were reacted at 80°C for 6 hours with uniform stirring to obtain a coating liquid (1) containing polyurethane (1). The number average molecular weight and weight average molecular weight of the resulting polyurethane (1) were measured using the following methods.

[0100] <Measurement of number average molecular weight and weight average molecular weight> The molecular weight was determined by gel permeation chromatography (GPC). The conditions were as follows: a high-speed GPC system (Tosoh Corporation, HLC-8320GPC) was used; one TSKgel guard column α (6.0 mm I.D. × 4 cm) and two +α-M (7.8 mm I.D. × 30 cm) columns were connected in series in the order indicated (all columns were manufactured by Tosoh Corporation). Cyclohexanone was used as the mobile phase, and the mobile phase flow rate was 1.0 mL / min. The column temperature was 40°C, and the detector was an RI detector (polarity (+)). The molecular weight was determined as a polystyrene-equivalent molecular weight. The sample solution was prepared in cyclohexanone to a concentration of 1 mg / mL. The sample injection volume was 100 μL.

[0101] <Production of goods> The coating solution (1) obtained above was applied to a polyethylene substrate (Kobe Poly Sheet EL-N-AN, manufactured by Hitachi Chemical Co., Ltd.) using a bar coater, left to stand at room temperature for 5 minutes, and then dried at 80°C for 5 minutes using a hot air dryer to obtain an unbonded article having an adhesive layer with a dry film thickness of 10 μm. Next, a polyethylene terephthalate film (Toyobo Ester Film E5100, manufactured by Toyobo Co., Ltd.) was laminated on top of the adhesive layer, and then heat-treated at 140°C for 10 minutes to obtain an article.

[0102] <Measurement of needle-like structure> The resulting article was cut into 1 cm square pieces using an ultramicrotome and exposed to ruthenium (IV) oxide vapor at atmospheric pressure for 20 minutes to dye the adhesive layer. The dyed sample was cooled to -125°C and cut using a cryomicrotome to obtain thin-film slices of the sample approximately 100 nm thick. These thin-film slices were observed using a transmission electron microscope (JEOL JEM-2100F) to obtain images of the cross section perpendicular to the bonding surface. Observations were performed at 25°C. In the obtained images, the length from the origin to the tip of the needle-like structure was measured and calculated based on a scale to determine the length of the needle-like structure. As a result of the measurement, it was confirmed that a large number of needle-like structures with lengths of 670 to 1017 nm were formed on the bonding surface between the substrate and the adhesive layer in the article of Example 1. An observed image of the article of Example 1 is shown in Figure 1(a). Note that the black dashed line in Figure 1(a) indicates the starting point of the needle-like structures, and the white dashed line indicates the tip of the longest needle-like structure.

[0103] <Measurement of adhesive strength> The adhesive strength of the resulting articles was evaluated by a 180-degree peel test in accordance with JIS K6854-2. The test was performed using an Autocom type testing machine (TSE UTPS-Acs(S)). The results are shown in Table 1.

[0104] Example 2 <Production of goods> The coating liquid (1) obtained in Example 1 was applied to a polypropylene substrate (Kobe Polysheet PP manufactured by Hitachi Chemical Co., Ltd.) using a bar coater, left to stand at room temperature for 5 minutes, and then dried at 80°C for 5 minutes using a hot air dryer to obtain an unbonded article having an adhesive layer with a dry film thickness of 10 μm. Next, a polyethylene terephthalate film (Toyobo Ester Film E5100 manufactured by Toyobo Co., Ltd.) was laminated on top of the adhesive layer, and then heat-treated at 185°C for 10 minutes to obtain an article. The needle-like structures of the obtained article were measured in the same manner as in Example 1. As a result, it was confirmed that a large number of needle-like structures with lengths of 57 to 105 nm were formed on the bonding surface between the substrate and the adhesive layer in the article of Example 2. The results are shown in Figure 1(b). The adhesive strength of the resulting article was measured in the same manner as in Example 1. The results are shown in Table 1.

[0105] Example 3 <Production of Polyurethane (2)> A 2-L four-neck separable flask equipped with a stirrer, thermometer, heater, and reflux condenser was charged with 149 g of hydroxyl-terminated hydrogenated polybutadiene, 33 g of MDI, 0.28 g of dioctyltin dilaurate, and 1,718 g of cyclohexanone at room temperature, and then nitrogen gas was blown in to replace the atmosphere inside the flask. These components were reacted at 80°C for 2 hours with uniform stirring, after which 8.7 g of 2-methyl-1,3-propanediol was added and the reaction continued for an additional 6 hours under the same conditions to obtain a coating solution (2) containing polyurethane (2). The number-average molecular weight and weight-average molecular weight of the resulting polyurethane (2) were measured using the same method as in Example 1.

[0106] <Production of goods> An article was produced in the same manner as in Example 1, except that the coating liquid (2) was used instead of the coating liquid (1). The needle-like structures of the obtained article were measured in the same manner as in Example 1. As a result, it was confirmed that a large number of needle-like structures with lengths of 417 to 790 nm were formed on the bonding surface between the substrate and the adhesive layer in the article of Example 3. The results are shown in Figure 1(c). The adhesive strength of the resulting article was measured in the same manner as in Example 1. The results are shown in Table 1.

[0107] Example 4 <Production of goods> An article was produced in the same manner as in Example 2, except that coating liquid (2) was used instead of coating liquid (1). The needle-like structures of the obtained article were measured in the same manner as in Example 1. As a result, it was confirmed that a large number of needle-like structures with lengths of 34 to 58 nm were formed on the bonding surface between the substrate and the adhesive layer in the article of Example 4. The results are shown in Figure 1(d). The adhesive strength of the resulting article was measured in the same manner as in Example 1. The results are shown in Table 1.

[0108] ( Reference example 1 ) <Production of Polyurethane (3)> A 2 L four-neck separable flask equipped with a stirrer, thermometer, heater, and reflux condenser was charged with 123 g of hydroxyl-terminated hydrogenated polybutadiene, 50 g of MDI, 0.42 g of dioctyltin dilaurate, and 1727 g of cyclohexanone at room temperature, and then nitrogen gas was blown in to replace the atmosphere inside the flask. After these were reacted for 2 hours with uniform stirring at 80°C, 19 g of 2-methyl-1,3-propanediol was added, and the reaction was continued for another 6 hours under the same conditions to obtain coating solution (3) containing polyurethane (3). of The number average molecular weight and weight average molecular weight of the obtained polyurethane (3) were measured in the same manner as in Example 1.

[0109] <Production of goods> An article was produced in the same manner as in Example 1, except that the coating liquid (3) was used instead of the coating liquid (1). The needle-like structure of the obtained article was measured in the same manner as in Example 1. As a result, Reference example 1 In this article, it was confirmed that numerous needle-like structures with lengths of 243 to 757 nm were formed on the bonding surface between the substrate and the adhesive layer. The results are shown in Figure 1(e). The adhesive strength of the resulting article was measured in the same manner as in Example 1. The results are shown in Table 2.

[0110] ( Reference example 2 ) <Production of goods> An article was produced in the same manner as in Example 2, except that the coating liquid (3) was used instead of the coating liquid (1). The needle-like structure of the obtained article was measured in the same manner as in Example 1. As a result, Reference example 2 In this article, it was confirmed that numerous needle-like structures with lengths of 11 to 47 nm were formed on the bonding surface between the substrate and the adhesive layer. The results are shown in Figure 1(f). The adhesive strength of the resulting article was measured in the same manner as in Example 1. The results are shown in Table 2.

[0111] ( Reference example 3 ) <Production of Polyurethane (4)> A 2 L four-neck separable flask equipped with a stirrer, thermometer, heater, and reflux condenser was charged with 96 g of hydroxyl-terminated hydrogenated polybutadiene, 67 g of MDI, 0.56 g of dioctyltin dilaurate, and 1736 g of cyclohexanone at room temperature, and then nitrogen gas was blown in to replace the atmosphere inside the flask. These components were reacted at 80°C for 2 hours with uniform stirring, after which 29 g of 2-methyl-1,3-propanediol was added and the reaction continued under the same conditions for an additional 6 hours to obtain a coating solution (4) containing polyurethane (4). The number-average molecular weight and weight-average molecular weight of the resulting polyurethane (4) were measured using the same method as in Example 1.

[0112] <Production of goods> An article was produced in the same manner as in Example 1, except that the coating liquid (4) was used instead of the coating liquid (1). The needle-like structure of the obtained article was measured in the same manner as in Example 1. As a result, Reference example 3 In this article, it was confirmed that numerous needle-like structures with lengths of 226 to 530 nm were formed on the bonding surface between the substrate and the adhesive layer. The results are shown in Figure 1(g). The adhesive strength of the resulting article was measured in the same manner as in Example 1. The results are shown in Table 2.

[0113] (Comparative Example 1) An article was produced in the same manner as in Example 2, except that the coating liquid (4) was used instead of the coating liquid (1). The needle-like structures of the obtained articles were measured in the same manner as in Example 1. As a result, no needle-like structures were confirmed at the bonding surface between the substrate and the adhesive layer in the article of Comparative Example 1. The results are shown in Figure 1(h). The adhesive strength of the resulting article was measured in the same manner as in Example 1. The results are shown in Table 2.

[0114] [Table 1]

[0115] [Table 2]

Claims

1. A substrate containing a polyolefin and an adhesive layer containing a polyurethane disposed on the substrate, The polyurethane has polyol units (A) and polyisocyanate units (B), the polyol unit (A) includes a first polyol unit (A-1) having an alkanediyl group having 40 or more carbon atoms, the first polyol unit (A-1) has a hydrogenated polybutadiene skeleton, the content of the first polyol units (A-1) is 90 mass% or more based on the total amount of the polyol units (A); The weight average molecular weight of the polyurethane is 8,000 or more and 26,000 or less, At the bonding surface between the substrate and the adhesive layer, needle-like structures containing polyolefin are formed, protruding from the substrate toward the adhesive layer. Goods.

2. the polyolefin is polyethylene, The article of claim 1 , wherein the needle-like structures comprise needle-like structures having a length of 250 nm or greater.

3. the polyolefin is polypropylene, The article of claim 1 , wherein the needle-like structures comprise needle-like structures having a length of 20 nm or more.

4. The article according to any one of claims 1 to 3, wherein the content of the polyol units (A) is 60 mass% or more based on the total amount of the polyurethane.

5. The article according to any one of claims 1 to 4, wherein the polyol units (A) include second polyol units (A-2) having an alkanediyl group having less than 40 carbon atoms.

6. The second polyol unit (A-2) is a structural unit derived from a second polyol (a-2) having an alkanediyl group having less than 40 carbon atoms, The article of claim 5, wherein the second polyol (a-2) is 2-methyl-1,3-propanediol or 3-methyl-1,5-pentanediol.

7. The article according to any one of claims 1 to 6, wherein the polyisocyanate units (B) include first polyisocyanate units (B-1) having an aromatic ring.

8. A first step of providing an unbonded article having a substrate containing a polyolefin and an adhesive layer containing a polyurethane disposed on the substrate; A second step of heating the bonding surface between the substrate and the adhesive layer of the unbonded article to obtain the article according to any one of claims 1 to 7; A method for manufacturing an article, comprising:

9. the article has the needle-like structures having a length of 20 nm or more at the bonding surface between the substrate and the adhesive layer, The method according to claim 8 , wherein the unbonded article does not have needle-like structures with a length of 20 nm or more at the bonding surface between the substrate and the adhesive layer.

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