JP7447475B2 - How to collect base materials - Google Patents

Description

The present invention relates to a method for removing an adhesive made from a moisture-curable polyurethane hot melt resin composition from a base material and recovering the base material.

Adhesives made from moisture-curable polyurethane hot-melt resin compositions are solvent-free, so various studies have been conducted to date on them as environmentally friendly adhesives, mainly for fiber bonding and construction material lamination, and they are widely used in industry. has been done.

In addition, in recent years, in response to the increasing need for lighter and thinner optical components when bonding optical components together, moisture-curing polyurethane hot melt adhesives have been substituted for the acrylic adhesives that have been the mainstream. Consideration is being given to

The adhesive may be, for example, (a) 100 parts by weight of a polyurethane resin with a flow start temperature of 55°C or higher and 110°C or lower, and (b) a saturated polyester resin with a Tg of 0°C or higher and 110°C or lower and a molecular weight of 10,000 to 25,000. 5 to 150 parts by weight, (c) 10 to 150 parts by weight of an epoxy resin with a softening point of 60°C to 140°C and a molecular weight of 700 to 3,000, and (d) 10 to 200 parts by weight of an inorganic filler surface-treated with a coupling agent. An adhesive using a heat-and-moisture resistant hot melt adhesive composition is disclosed (for example, see Patent Document 1).

Since the laminate obtained using the adhesive has strong adhesive strength, it has an advantageous effect in terms of adhesiveness. However, on the other hand, there was a problem in that the base material could not be reworked because it could not be peeled off. In particular, now that moisture-curing polyurethane hot-melt adhesives are increasingly being used for bonding optical components, expensive substrates (adherends) such as display parts such as liquid crystal panels and housings are being used. is often used, there is a strong demand for improved reworkability of the base material by peeling off the adhesive.

Japanese Patent Application Publication No. 2003-27030

The problem to be solved by the present invention is to provide a method that has excellent releasability between a cured film of a moisture-curable polyurethane hot melt resin composition and a base material, and allows reworking of the base material.

The present invention is a method for recovering a substrate by heating a laminate having a substrate and a cured film of a moisture-curable polyurethane hot-melt resin composition, the method comprising: The present invention provides a method for recovering a substrate, characterized in that the gel fraction of the cured film is 80% by mass or more.

According to the method of the present invention, the peelability between the cured film of the moisture-curable polyurethane hot melt resin composition and the base material is excellent, and excellent rework of the base material can be obtained.

It is essential that the moisture-curable polyurethane hot melt resin composition used in the present invention has a cured film having a gel fraction of 80% by mass or more. If the gel fraction is within this range, the cured film is a dense and strong film that can be easily peeled off from the base material by heating, the cured film will not break, and the adhesive will not break. All reusable base materials can be recovered (hereinafter abbreviated as "base material reworkability"). The gel fraction of the cured film is preferably in the range of 80 to 100% by mass, more preferably in the range of 85 to 100% by mass, from the standpoint of obtaining even better reworkability of the base material. The method for measuring the gel fraction of the cured film will be described in detail in Examples.

Examples of the moisture-curable polyurethane hot melt resin composition include those containing an isocyanate group-containing urethane prepolymer (i) made from polyol (A) and polyisocyanate (B).

As the polyol (A), for example, polyester polyol, polyether polyol, polycarbonate polyol, polyacrylic polyol, polybutadiene polyol, etc. can be used. These polyols may be used alone or in combination of two or more.

As the polyol (A), among those mentioned above, polyether polyol (a1), because it can express excellent adhesiveness and it is easy to adjust the gel fraction of the cured film to the range specified in the present invention, It contains a polyacrylic polyol (a2), a crystalline polyester polyol (a3), and a polycarbonate polyol (a4). It is preferable to contain a crystalline polyester polyol (a5).

The polyether polyol (a1) can soften the adhesive film and improve adhesion to any base material, and includes, for example, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyoxyethylene polyoxypropylene. Polyol, polyoxyethylene polyoxytetramethylene polyol, polyoxypropylene polyoxytetramethylene polyol, etc. can be used. These polyether polyols may be used alone or in combination of two or more. Among these, polyoxyethylene polyoxypropylene polyol is preferable because the adhesive film becomes even more flexible and excellent adhesiveness can be obtained even to difficult-to-adhesive substrates.

The polyoxyethylene polyoxypropylene polyol can be produced, for example, by addition polymerization of an initiator made of a compound having two or more active hydrogen atoms and an alkylene oxide containing ethylene oxide and propylene oxide. Can be done. Specifically, in the presence of the initiator, the alkylene oxide, etc. can be mixed all at once, or each can be separately supplied, mixed, and reacted.

As the initiator, for example, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylolpropane, etc. can be used. Moreover, as the alkylene oxide, in addition to ethylene oxide and propylene oxide, butylene oxide can be used in combination as necessary.

The molar ratio [EO/PO] of oxyethylene groups (EO) and oxypropylene groups (PO) in the polyoxyethylene polyoxypropylene polyol provides even better adhesion to difficult-to-adhesive substrates. From this point of view, the range of 5/95 to 90/10 is preferable, and the range of 5/95 to 50/50 is more preferable.

The average number of functional groups (hydroxyl groups) of the polyoxyethylene polyoxypropylene polyol is preferably in the range of 1.5 to 3, from the viewpoint of obtaining even better adhesion to difficult-to-adhesive substrates, and 1.5 The range of ˜2.5 is more preferable.

The number average molecular weight of the polyoxyethylene polyoxypropylene polyol is preferably in the range of 500 to 10,000, and more preferably in the range of 700 to 7,000, from the viewpoint of obtaining even better adhesion to difficult-to-adhesive substrates. is more preferable. The number average molecular weight of the polyoxyethylene polyoxypropylene polyol (a1) is a value measured by gel permeation chromatography (GPC).

The amount of the polyether polyol (a1) to be used is preferably in the range of 5 to 50% by mass in the raw materials constituting the urethane prepolymer (i), and 10 to 40% by mass, from the viewpoint of obtaining even better adhesiveness. % range is more preferred.

The polyacrylic polyol (a2) has excellent drop impact resistance, and for example, a polymer of a (meth)acrylic compound that essentially contains a (meth)acrylic compound having a hydroxyl group can be used. . In the present invention, "(meth)acrylic compound" refers to one or both of a methacrylic compound and an acrylic compound, and "(meth)acrylate" refers to one or both of methacrylate and acrylate.

As the (meth)acrylic compound having a hydroxyl group, for example, 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, hydroxybutyl (meth)acrylate, etc. can be used. These compounds may be used alone or in combination of two or more. The (meth)acrylic compound having a hydroxyl group is preferably 2-hydroxyethyl (meth)acrylate.

Examples of other (meth)acrylic compounds include (meth)acrylic acid, methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, isobutyl (meth)acrylate, and tert-butyl (meth)acrylate. Acrylate, neopentyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, stearyl (meth)acrylate, isostearyl (meth)acrylate, cetyl (meth)acrylate, lauryl (meth)acrylate, etc. (meth)acrylic acid alkyl ester (meth)acrylic acid alkyl ester; 2,2,2-trifluoroethyl (meth)acrylate, 2,2,3,3-tetrafluoropropyl (meth)acrylate, 1H, 1H, 5H - (Meth)acrylic compounds having a fluorine atom such as octafluoropentyl (meth)acrylate, 2-(perfluorooctyl)ethyl (meth)acrylate; isobornyl (meth)acrylate, cyclohexyl (meth)acrylate, cydiclopentanyl ( (Meth)acrylic compounds having an alicyclic structure such as meth)acrylate, dicyclopentenyloxyethyl (meth)acrylate; polyethylene glycol mono(meth)acrylate, methoxyethyl (meth)acrylate, methoxybutyl (meth)acrylate, methoxytri (Meth)acrylic compounds having ether groups such as ethylene glycol (meth)acrylate and methoxypolyethylene glycol (meth)acrylate; benzyl (meth)acrylate, 2-ethyl-2-methyl-[1,3]-dioxolane-4- yl-methyl (meth)acrylate, dimethylaminoethyl (meth)acrylate, etc. can be used. These compounds may be used alone or in combination of two or more. Among these, (meth)acrylic acid alkyl esters are preferred from the viewpoint of obtaining even better adhesion and drop impact resistance, and methyl (meth)acrylate and/or n-butyl (meth)acrylate are preferred. is more preferable.

The number average molecular weight of the acrylic polyol (a2) is preferably in the range of 5,000 to 100,000, and 10,000 to 30, from the viewpoint of obtaining even better drop crystallization resistance and adhesive properties. ,000 is more preferable. The number average molecular weight of the acrylic polyol (a2) is a value measured by gel permeation chromatography (GPC).

The glass transition temperature of the acrylic polyol (a2) is preferably in the range of -50 to 120°C, and preferably in the range of -35 to 80°C, from the viewpoint of obtaining even better drop impact resistance and adhesive properties. More preferred. The glass transition temperature of the acrylic polyol (a2) is a value measured by DSC in accordance with JIS K 7121-1987. ), the temperature was raised to (Tg + 50 °C) at a heating rate of 10 °C/min, held for 3 minutes, then rapidly cooled, and the midpoint glass transition temperature (Tmg) read from the obtained differential thermal curve is shown. .

The amount of the acrylic polyol (a2) to be used is in the range of 5 to 40% by mass in the raw materials constituting the urethane prepolymer (i) in order to obtain even better drop impact resistance and adhesive properties. It is preferably in the range of 10 to 30% by mass.

The crystalline polyester polyol (a3) provides excellent adhesiveness due to its cohesive force, and for example, a reaction product of a compound having a hydroxyl group and a polybasic acid can be used. In the present invention, "crystalline" refers to a property in which a peak of heat of crystallization or heat of fusion can be confirmed in DSC (differential scanning calorimeter) measurement in accordance with JISK7121:2012, and "amorphous" indicates that the peak cannot be confirmed.

As the compound having a hydroxyl group, for example, ethylene glycol, propylene glycol, butanediol, pentanediol, hexanediol, heptanediol, octanediol, nonanediol, decanediol, trimethylolpropane, trimethylolethane, glycerin, etc. may be used. Can be done. These compounds may be used alone or in combination of two or more. Among these, it is preferable to use one or more selected from the group consisting of butanediol, hexanediol, octanediol, and decanediol from the viewpoint of increasing crystallinity and obtaining even more excellent adhesiveness.

As the polybasic acid, for example, oxalic acid, malonic acid, succinic acid, adipic acid, sebacic acid, azelaic acid, dodecanedioic acid, etc. can be used. These compounds may be used alone or in combination of two or more.

The number average molecular weight of the crystalline polyester polyol (a3) is preferably in the range of 500 to 10,000, more preferably in the range of 1,000 to 4,000, from the standpoint of obtaining even better adhesiveness. The number average molecular weight of the crystalline polyester polyol (a3) is a value measured by gel permeation chromatography (GPC).

The amount of the crystalline polyester polyol (a3) to be used is preferably in the range of 5 to 40% by mass, and 10 to 30% by mass based on the raw materials constituting the urethane prepolymer (i), in order to obtain even better adhesiveness. A range of mass % is more preferable.

The polycarbonate polyol (a4) can ensure excellent adhesiveness, and for example, a reaction product of a compound having two or more hydroxyl groups and a carbonate ester and/or phosgene can be used.

Glass transition temperature of acrylic polyol (a2), decanediol, caprolactone, cyclohexanedimethanol, 3-methyl-1,5-pentanediol, neopentyl glycol, isosorbide, etc. can be used. These compounds may be used alone or in combination of two or more.

As the carbonate ester, for example, dimethyl carbonate, diethyl carbonate, diphenyl carbonate, ethylene carbonate, propylene carbonate, etc. can be used. These compounds may be used alone or in combination of two or more.

The polycarbonate polyol (a4) is preferably a polycarbonate polyol (a4) that is liquid at room temperature because it provides even better drop impact resistance. In the present invention, the term "liquid at room temperature" means that the polycarbonate polyol (a4) is liquid or viscous and exhibits fluidity at 23°C.

The number average molecular weight of the polycarbonate diol (a4) is preferably in the range of 500 to 10,000, more preferably in the range of 700 to 4,000, from the standpoint of obtaining even better adhesiveness. The number average molecular weight of the polycarbonate polyol (a4) is a value measured by gel permeation chromatography (GPC).

The amount of the polycarbonate diol (a4) to be used is preferably in the range of 1 to 15% by mass, and 3 to 10% by mass in the raw materials constituting the urethane prepolymer (i), in order to obtain even better adhesiveness. The range is more preferable.

The amorphous polyester polyol (a5) made from the alkylene oxide adduct of bisphenol A has a role as a compatibilizer that improves compatibility with other polyols, and when used, it produces dense and strong It is preferable because it can form an adhesive film.

Specific examples of the amorphous polyester polyol (a5) include a reaction product of a compound having two or more hydroxyl groups, including an alkylene oxide adduct of bisphenol A, and a polybasic acid.

As the alkylene oxide in the alkylene oxide adduct of bisphenol A, for example, ethylene oxide, propylene oxide, butylene oxide, etc. can be used. These alkylene oxides may be used alone or in combination of two or more. Among these, propylene oxide is preferred because it further improves its role as a compatibilizer. The number of moles of the alkylene oxide added is preferably in the range of 2 to 10 moles, more preferably in the range of 4 to 8 moles.

The alkylene oxide adduct of bisphenol A may optionally include ethylene glycol, propylene glycol, 1,4-butanediol, pentanediol, 2,4-diethyl-1,5-pentanediol, 3-methyl-1 , 5-pentanediol, hexanediol, neopentyl glycol, hexamethylene glycol, glycerin, trimethylolpropane, etc. may be used in combination. These compounds may be used alone or in combination of two or more.

Examples of the polybasic acids include adipic acid, glutaric acid, pimelic acid, suberic acid, dimer acid, sebacic acid, undecanedicarboxylic acid, hexahydroterephthalic acid, phthalic acid, phthalic anhydride, isophthalic acid, and terephthalic acid. Can be used. These compounds may be used alone or in combination of two or more.

The number average molecular weight of the amorphous polyester polyol (a5) is preferably in the range of 500 to 10,000, and preferably in the range of 1,000 to 4,000, from the viewpoint of further improving its role as a compatibilizer. More preferably, the range is from 1,000 to 3,000.

The glass transition temperature of the amorphous polyester polyol (a5) is preferably in the range of -70 to -10°C from the viewpoint of further improving its role as a compatibilizer. Note that the glass transition temperature of the amorphous polyester polyol (a5) is the same as the method for measuring the glass transition temperature of the acrylic polyol (a2).

The amount of the amorphous polyester polyol (a5) to be used is in the range of 0.5 to 10% by mass in the raw material constituting the urethane prepolymer (i), since it further improves its role as a compatibilizer. It is preferably in the range of 1 to 7% by mass.

Examples of the polyisocyanate (B) include aromatic polyisocyanates such as polymethylene polyphenyl polyisocyanate, diphenylmethane diisocyanate, carbodiimide-modified diphenylmethane diisocyanate isocyanate, phenylene diisocyanate, tolylene diisocyanate, and naphthalene diisocyanate; hexamethylene diisocyanate, lysine diisocyanate, Aliphatic or alicyclic polyisocyanates such as cyclohexane diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, xylylene diisocyanate, and tetramethylxylylene diisocyanate can be used. Among these, aromatic polyisocyanates are preferred, and diphenylmethane diisocyanate is more preferred, since even better reactivity and adhesiveness can be obtained.

In addition, the amount of the polyisocyanate (B) used is preferably in the range of 1 to 25% by mass, and 5 to 15% by mass based on the raw materials constituting the urethane prepolymer (i), from the viewpoint of obtaining even better adhesiveness. A range of mass % is more preferable.

The urethane prepolymer (i) is obtained by reacting the polyol (A) with the polyisocyanate (B), and can be dissolved in the air or in the housing or adherend to which the urethane prepolymer is applied. It has an isocyanate group at the end of the polymer or within the molecule that can react with existing moisture to form a crosslinked structure.

As a method for producing the urethane prepolymer (i), for example, the polyol (A) is dropped into a reaction vessel containing the polyisocyanate (B), and then heated, and the isocyanate groups of the polyisocyanate (B) are dissolved. can be produced by reacting under conditions in which the polyol (A) has an excess of hydroxyl groups relative to the hydroxyl groups possessed by the polyol (A).

The isocyanate group content (hereinafter abbreviated as "NCO%") of the urethane prepolymer (i) is 1 to 3 mass by weight in order to obtain even better adhesion and drop impact resistance. % range is preferred, and a range of 1.3 to 2% by weight is more preferred. Note that the NCO% of the urethane prepolymer (i) is a value measured by potentiometric titration in accordance with JIS K1603-1:2007.

The moisture-curable polyurethane hot melt resin composition used in the present invention contains the urethane prepolymer (i) as an essential component, but may contain other additives as necessary.

Examples of the other additives include antioxidants, tackifiers, plasticizers, stabilizers, fillers, dyes, pigments, optical brighteners, silane coupling agents, and wax. These additives may be used alone or in combination of two or more.

Next, the laminate will be explained.

The laminate includes a base material and a cured film of the moisture-curable polyurethane hot melt resin composition.

Examples of the base material include acrylic resin, urethane resin, silicone resin, epoxy resin, fluorine resin, polystyrene resin, polyester resin, polysulfone resin, polyarylate resin, polyvinyl chloride resin, Polyvinylidene chloride, cycloolefin resin, polyolefin resin, polyimide resin, alicyclic polyimide resin, cellulose resin, PC (polycarbonate), PBT (polybutylene terephthalate), modified PPE (polyphenylene ether), PEN (polyethylene) Resin films such as naphthalate), PET (polyethylene terephthalate), lactic acid polymer, ABS resin, and AS resin; Wooden base materials such as MDF, plywood, and particle board; Fiber base materials such as nonwoven fabrics, woven fabrics, and knitted fabrics; Stainless steel and aluminum Metal base materials such as copper, steel, chromium, zinc, duralumin, die casting, and alloys thereof can be used. The base material may be subjected to corona treatment, plasma treatment, primer treatment, etc., as necessary.

As a method for applying the moisture-curable polyurethane hot melt resin composition to the substrate, for example, a roll coater, a spray coater, a T-tie coater, a knife coater, a comma coater, etc. can be used. Furthermore, since the reactive hot melt resin has low viscosity and shape retention properties after application, it can also be applied by methods such as dispenser, inkjet printing, screen printing, and offset printing. These coating methods are preferable because the reactive hot melt resin can be applied to the desired location on the member, and no loss occurs during punching or the like. Furthermore, according to these coating methods, the reactive hot melt resin is applied to the base material in various shapes such as dots, lines, triangles, squares, circles, and curves, either continuously or intermittently. It can be formed as follows.

The thickness of the cured layer of the moisture-curable polyurethane hot melt resin composition can be set depending on the intended use, and can be preferably set within the range of, for example, 10 μm to 5 mm.

The aging conditions for the moisture-curable polyurethane hot melt resin composition after the bonding are, for example, appropriately determined at a temperature of 20 to 80°C, a relative humidity of 50 to 90% RH, and 0.5 to 5 days. Can be done.

By the above method, a laminate having at least two layers, the base material and the cured layer of the moisture-curable polyurethane hot melt resin composition, which are firmly adhered to each other, can be obtained.

Next, the method for recovering the base material of the present invention will be explained.

The method for recovering a substrate of the present invention is to recover the substrate by heating the substrate and the laminate having a cured film of the moisture-curable polyurethane hot melt resin composition.

The heating may be carried out, for example, at 40 to 120° C. for 1 to 30 minutes.

As described above, according to the method of the present invention, the peelability between the cured film of the moisture-curable polyurethane hot melt resin composition and the base material is excellent, and excellent rework of the base material can be obtained.

Hereinafter, the present invention will be explained in more detail with reference to Examples.

[Synthesis example 1]
In a four-necked flask equipped with a thermometer, stirrer, inert gas inlet, and reflux condenser, polyoxyethylene polyoxypropylene glycol ("Preminol PML-5001" manufactured by Asahi Glass Co., Ltd., number average molecular weight: 4,000, EO/PO molar ratio = 〇/〇, average number of functional groups: 2, hereinafter abbreviated as "EOPO (1)". 13 parts by mass, polyacrylic polyol (methyl methacrylate) , n-butyl methacrylate, and 2-hydroxyethyl methacrylate, number average molecular weight: 20,000, glass transition temperature: 70°C, hereinafter abbreviated as "Ac(1)"), 18 parts by mass, crystallinity 26 parts by mass of polyester polyol (reactant of 1,6-hexanediol and adipic acid, number average molecular weight: 2,000, hereinafter abbreviated as "HG/AA"), polycarbonate polyol ("Duranol T5652" manufactured by Asahi Kasei Corporation) ", number average molecular weight: 2,000, hereinafter abbreviated as "PC (1)") 5 parts by mass, amorphous polyester polyol (6 mole adduct of propene oxide of bisphenol A, isophthalic acid, and sebacic acid) 5 parts by mass of the reactant (number average molecular weight: 2,000, hereinafter abbreviated as "BISA6PO") was dehydrated by heating at 90°C until the water content was 0.05% by mass or less. .
Next, after cooling the temperature inside the container to 60°C, 13 parts by mass of diphenylmethane didiisocyanate (hereinafter abbreviated as "MDI") was added, the temperature was raised to 110°C, and the temperature was kept at about 30°C until the isocyanate group content became constant. The mixture was reacted for a period of time to obtain a urethane prepolymer (i-1) having isocyanate groups, and a moisture-curable polyurethane hot melt resin composition was obtained.

[Synthesis example 2]
In Example 1, Ac(1) was replaced with polyacrylic polyol (a reaction product of n-butyl acrylate, n-butyl methacrylate, and 2-hydroxyethyl methacrylate, number average molecular weight: 7000, glass transition temperature: -28. A urethane prepolymer (i-2) having an isocyanate group was obtained in the same manner as in Example 1, except that 5°C (hereinafter abbreviated as "Ac(2)") was used, and a moisture-curable polyurethane hot melt was obtained. A resin composition was obtained.

[Synthesis example 3]
In Example 1, instead of HG/AA, a crystalline polyester polyol (a reaction product of 1,6-hexanediol and sebacic acid, number average molecular weight: 3,500, hereinafter abbreviated as "HG/SEBA") was used. A urethane prepolymer (i-3) having an isocyanate group was obtained in the same manner as in Example 1 except that a moisture-curable polyurethane hot melt resin composition was obtained.

[Comparative synthesis example 1]
In a four-necked flask equipped with a thermometer, a stirrer, an inert gas inlet, and a reflux condenser, 20 parts by mass of EOPO (1), 13 parts by mass of EOPO (2), 18 parts by mass of Ac (1), 31 parts by mass of HG/AA and 5 parts by mass of PC(1) were charged and heated at 90°C to dehydrate until the water content became 0.05% by mass or less.
Next, after cooling the temperature inside the container to 60°C, 13 parts by mass of MDI was added, the temperature was raised to 110°C, and the reaction was carried out for about 3 hours until the isocyanate group content became constant. -1) was obtained, and a moisture-curable polyurethane hot melt resin composition was obtained.

[Example 1]
[Method for producing laminate]
The moisture-curable polyurethane hot melt resin composition obtained in Synthesis Example 1 was heated and melted at 110°C, and a dispenser needle (dispenser "VAVE" manufactured by Musashi Engineering Co., Ltd., manufactured by Musashi Engineering Co., Ltd.) having an inner diameter of 0.35 mm was heated to 110°C. MASTER ME-5000VT"), at a discharge pressure of 0.3 MPa and a processing speed of 50 mm/sec, a 1-inch circular shape was placed on a PC board (5 cm x 9 cm) with a 1 cm diameter hole in the center. After applying the coating to a thickness of 0.15 mm and pasting a PBT plate (5 cm x 5 cm) on top of it, it was laminated by leaving it in a constant temperature and humidity chamber at a temperature of 23°C and a humidity of 50% for 24 hours. I got a body.

[Method for evaluating reworkability of base material]
(1) Evaluation based on adhesive strength After the obtained laminate was left in a temperature environment of 75°C for 10 minutes, the push strength was measured using Tensilon (Tensilon universal testing machine "RTC-1210A" manufactured by Orientech Co., Ltd.). The following evaluation was made based on the values measured at a crosshead speed of 10 mm/min.
"A"; Less than 200 N/cm ² "B"; 200 N/cm ² or more and 250 N/cm less than ² "C"; 250 N/cm ² or more (2) Evaluation by appearance The PBT board after measuring the push strength described above. The appearance was visually observed and evaluated as follows.
"〇": No adhesive residue.
"×": There is adhesive residue.

[Method of measuring gel fraction]
The moisture-curable polyurethane hot melt resin composition obtained in Synthesis Example 1 was melted at 110°C for 1 hour, and then coated on release paper using a roll coater so that the film thickness after curing was 100 μm. , 23°C and 50% humidity for 2 days to obtain a cured film.
This cured film was cut into pieces of 3 cm in length and 3 cm in width, and the mass (X) was measured. Next, the test piece was immersed in 50 ml of toluene adjusted to 25°C for 24 hours, and the film residue that did not dissolve in toluene was dried at 108°C for 1 hour, and the mass (Y) was measured. From the obtained mass (X) and mass (Y), the gel fraction is calculated using the formula (Y) x (X) x 100, and is displayed as follows.
"A"; 80% by mass or more "B"; 75% by mass or more and less than 80% by mass "C"; less than 75% by mass

[Examples 2 to 3 and Comparative Example 1]
The gel fraction was measured in the same manner as in Example 1, a laminate was obtained, and the reworkability was evaluated in the same manner as in Example 1, except that the type of moisture-curable polyurethane hot melt resin composition used was changed as shown in Table 1. Ta.

[Method for measuring number average molecular weight]
The number average molecular weights of the polyols used in the synthesis examples and comparative synthesis examples are the values measured by gel permeation chromatography (GPC) under the following conditions.

Measuring device: High-speed GPC device (“HLC-8220GPC” manufactured by Tosoh Corporation)
Column: The following columns manufactured by Tosoh Corporation were used by connecting them in series.
"TSKgel G5000" (7.8mm I.D. x 30cm) x 1 "TSKgel G4000" (7.8mm I.D. x 30cm) x 1 "TSKgel G3000" (7.8mm I.D. x 30cm) x 1 Book "TSKgel G2000" (7.8mm I.D. x 30cm) x 1 Detector: RI (differential refractometer)
Column temperature: 40℃
Eluent: Tetrahydrofuran (THF)
Flow rate: 1.0 mL/min Injection volume: 100 μL (Tetrahydrofuran solution with sample concentration 0.4% by mass)
Standard sample: A calibration curve was created using the following standard polystyrene.

(Standard polystyrene)
"TSKgel standard polystyrene A-500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-1000" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-2500" manufactured by Tosoh Corporation
"TSKgel standard polystyrene A-5000" manufactured by Tosoh Corporation
“TSKgel Standard Polystyrene F-1” manufactured by Tosoh Corporation
"TSKgel Standard Polystyrene F-2" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-4" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-10" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-20" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-40" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-80" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-128" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-288" manufactured by Tosoh Corporation
"TSKgel standard polystyrene F-550" manufactured by Tosoh Corporation

It was found that the method of the present invention has excellent reworkability of the base material.

On the other hand, in Comparative Example 1, the gel fraction of the cured film was lower than the range specified by the present invention, but the reworkability of the base material was poor.

Claims (2)

A method for recovering a substrate by heating a laminate having a substrate and a cured film of a moisture-curable polyurethane hot melt resin composition, the method comprising:
The gel fraction of the cured film of the moisture-curable polyurethane hot melt resin composition is 80% by mass.
That's all,
The moisture-curable polyurethane hot melt resin composition
It contains a urethane prepolymer (i) having isocyanate groups made from polyol (A) and polyisocyanate (B),
The polyol (A) is a reaction product of polyether polyol (a1), methyl methacrylate, n-butyl methacrylate, and 2-hydroxyethyl methacrylate, or n-butyl acrylate, n-butyl methacrylate, and 2-hydroxyethyl methacrylate. Contains a polyacrylic polyol (a2), a crystalline polyester polyol (a3), a polycarbonate polyol (a4), which is a reaction product of A method for recovering a base material, characterized in that the base material is
. The method for recovering a substrate according to claim 1 , wherein the heating is at 50°C or higher.