A hot melt adhesive is a 100 % solids thermoplastic adhesive that is melted, applied as a liquid in a typical range of 121 to 204 °C (250 to 400 °F) (Henkel) and develops its bond by cooling. Built from industrial adhesive chemicals, it is a formulated blend of a base polymer, a tackifying resin, a wax or oil and an antioxidant, each with its own job in the melt and in the joint.
Five hot melt chemistries cover industrial bonding: ethylene-vinyl acetate (EVA) hot melts, polyolefin hot melts, hot melt pressure-sensitive adhesives (PSA), polyamide and polyester hot melts, and reactive polyurethane hot melts. A sixth discipline, hot melt application, covers melt temperature, equipment and char for all five.
The sections below give the wt % share of each raw material, two published starting formulas (EVA and amorphous poly-alpha-olefin, APAO) that set in 1.3 and 5.5 seconds, test methods with editions including three ASTM methods withdrawn in 2021, the conditions of 21 CFR 175.105, the EU diisocyanate training rule and a selection table that starts from service temperature.
Sources and checks: identities and hazard classifications are read at ECHA and the issuing regulator, standards at the body that publishes them, and grade values at the data sheet named next to them; methodology and fact-checking explains each step.
What Is a Hot Melt Adhesive?#
A hot melt adhesive is an adhesive that is thermally melted and develops cohesion by cooling, as defined in EN 923:2015 (cited by IVK Technical Briefing Note 4, March 2015). IVK is the German adhesives industry association. The definition rules out drying: a thermoplastic hot melt carries no water or solvent that must leave the joint, so the bond forms as soon as the melt turns solid between the two substrates.
IVK names five polymer families as the backbone of industrial hot melts. Ethylene-vinyl acetate copolymer (EVA) is the standard base; polyolefins (PO) and polyamides (PA) give higher thermal stability; reactive polyurethanes (PUR) add high thermal stability and moisture resistance; and polyesters (PES) offer a wider adhesion spectrum with a long open time. Each family fixes the processing window and service limits of the finished adhesive.
How Does a Hot Melt Adhesive Bond and Set?#
A hot melt adhesive bonds by wetting the substrate while it is liquid and sets as it loses heat. Wetting happens only in the liquid state: as heat flows from the bead into the substrate and the surrounding air, viscosity and surface tension rise until the adhesive no longer flows into the surface.
How adhesives cure differs by route: evaporation, cooling, chemical reaction and radiation. A thermoplastic hot melt uses cooling alone, so its open time and setting time are process settings rather than fixed adhesive constants, a point covered with the other routes under how adhesives cure.
Nothing evaporates during this cycle, so a thermoplastic hot melt is 100 % solids. H.B. Fuller states that solvent-based adhesives lose 50 to 70 % of their applied weight as the carrier leaves (producer statement, 2024-08-29), while a hot melt keeps all of its applied weight in the bond line.
Thermoplastic and Reactive Hot Melts#
Hot melt adhesives split into thermoplastic grades, which re-melt on heating, and reactive grades, which crosslink after cooling into a thermoset. Reactive polyurethane (PUR) hot melts and silane-grafted polyolefin (POR) hot melts form the second group in the IVK description. The split decides heat resistance: a crosslinked joint no longer melts.
Reactive PUR hot melts set in two steps, like other moisture-curing polyurethane adhesives. Carbonell Blasco and co-workers at INESCOP (Polymers, 2022) describe the first step as crystallization of the polyester segments, which gives green strength like a conventional hot melt; in the second, free isocyanate (NCO) groups of the prepolymer react with moisture from air or substrate to urea links and release carbon dioxide, the cure shared with one-part polyurethane adhesives.
Final strength of a reactive hot melt arrives days after the bond is made. Henkel data sheets give 2 to 5 days for TECHNOMELT PUR 4663 (September 2023) and PUR 3460 (October 2025) and 3 to 7 days for PUR 9720 (page read 2026-11-02), all typical product values, with the rate set by room and substrate humidity, substrate permeability and film weight.
What Is Hot Melt Adhesive Made Of?#
Hot melt adhesive is made of a thermoplastic base polymer, a tackifying resin, a wax or oil and an antioxidant: the polymer gives strength and flexibility, the resin wetting and adhesion, the wax viscosity, open time and set speed. Fillers and pigments join in some grades, and reactive grades replace the thermoplastic polymer with an isocyanate-terminated prepolymer. The table below lists the seven raw-material functions with the substances used for each and the shares published for them, every share with its basis and source.
| Function | Family hub | Substances | Share in hot melts (basis, source) |
|---|---|---|---|
| Base polymer | base polymers for adhesives | EVA, ethylene acrylate copolymers (EnBA, EMA), APAO, metallocene polyolefins, SIS, SBS, SEBS, polyamide resins | ethylene copolymer (EVA in the examples) 40 to 85 wt % (US20160230051A1 claim); APAO 55 wt % or more (US20120328805A1); metallocene PO 10 to 50 wt % (EP3541887B1); SBC 43 wt % (tape) and 30 wt % (elastic attachment) in 2 examples of ExxonMobil/Dexco (ASI 2009); polyamide resin up to the whole adhesive (Bostik producer statement) |
| Reactive backbone | isocyanates and polyols | polyurethane prepolymers, polyester polyols, polyether polyols, thermoplastic polyurethanes | NCO/OH index 1.5 in a published synthesis (Carbonell Blasco et al. 2022); TPU 10 to 15 wt % improves green strength (laboratory, 2024) |
| Tackifier | tackifier resins | hydrocarbon resins, rosin esters, polyterpene resins | up to 50 wt % of formulation (EP1976953B1); midblock resin 52 and 50 wt % in the same 2 SBC examples |
| Wax | waxes for hot melt adhesives | paraffin wax, microcrystalline wax, Fischer-Tropsch wax, polyethylene waxes | up to 50 wt % (EP1976953B1); synthetic wax 15 to 35 wt % (Fischer-Tropsch in Example 6; US20160230051A1 claim); grafted Licocene PP MA 3 to 5 %, basis not stated (Clariant page, 2026-11-02) |
| Plasticizer, oil | plasticizers for adhesives | process oils | 4 and 15 wt % in the same 2 SBC examples |
| Antioxidant | antioxidants for adhesives | antioxidant 1010, antioxidant 168 | up to about 2 wt %, often 0.1 to 1.5 wt % of formulation (frequency as stated in EP1976953B1) |
| Filler, pigment | fillers for adhesives | calcium carbonate | share not stated; chalk and barite set rheology and structure (IVK) |
Base Polymers: The Backbone of the Hot Melt#
Ethylene-vinyl acetate copolymer is the base polymer of the standard hot melt, and its vinyl acetate (VA) content sets how it melts. A 2021 review by Wu and co-workers in Polymers gives a VA range of 6 to 40 wt % for hot melt grades. In the ExxonMobil Escorene Ultra Europe grade slate of 2017, peak melting falls from 91 °C at 14 % VA through 71 °C at 27.5 % VA to 48 °C at 39 % VA (typical product values). Ethylene n-butyl acrylate copolymer (EnBA) can be combined with EVA in a packaging hot melt (US20160230051A1).
Amorphous poly-alpha-olefins (APAO), metallocene polyolefins and olefin block copolymers (OBC) form the polyolefin family, with APAO at 55 wt % or more of the formula in patent US20120328805A1. Styrenic block copolymers (SBC), such as styrene-isoprene-styrene (SIS), styrene-butadiene-styrene (SBS) and styrene-ethylene/butylene-styrene (SEBS), carry the pressure-sensitive grades. Dimer-acid polyamides, made by reacting dimerized fatty acids with diamines, and copolyesters serve the high-temperature end, and isocyanate-terminated (NCO) prepolymers form the backbone of reactive grades.
Tackifying Resins: Wetting and Specific Adhesion#
Tackifying resins give a hot melt its wetting and specific adhesion, at up to 50 wt % of the formulation. Patent EP1976953B1 (priority 2005-12-30) sets tackifier and wax each at up to 50 wt %, and at about 5 to 45 wt % each when both are used, next to a copolymer blend of 50 to 90 wt % in one embodiment. The packaging claim of US20160230051A1, built on an ethylene copolymer (EVA in the examples), caps the tackifier at about 27 wt %.
Three resin classes supply the tackifier: hydrocarbon resins, rosin esters such as the glycerol ester of rosin, and polyterpene resins. Shares vary widely between published examples: in patent US6605680B1 an EVA packaging hot melt of EVA 30 / resin 45 / wax 25 / antioxidant 0.2 parts carries about 45 wt % resin (calculated), above the cap of that claim.
Waxes: Viscosity, Open Time and Set Speed#
Waxes lower the melt viscosity of a hot melt and control its open time and set speed. Patent EP1976953B1 describes paraffin waxes with a melting point of about 55 to 85 °C and allows up to 50 wt % wax, while the claim of US20160230051A1 uses 15 to 35 wt % synthetic wax (Fischer-Tropsch in Example 6), which also lifts heat resistance in that patent.
Paraffin wax lowers viscosity and speeds set, while microcrystalline wax adds flexibility, temperature resistance and durability, so blends of the two balance set speed against cold and heat performance. Polyethylene waxes act as viscosity and setting modifiers. Maleic-anhydride-grafted polypropylene waxes add adhesion to polar substrates at small additions, listed with their source in the raw-material table.
Plasticizers and Oils in Hot Melt PSAs#
Plasticizers and process oils give a hot melt elasticity and lower its viscosity, a role found in hot melt pressure-sensitive adhesives (HMPSA). In the two styrenic block copolymer examples of the composition table, the elastic-attachment formula carries almost four times the oil of the tape formula.
Oil and midblock resin together lower the storage modulus of the adhesive until it stays permanently tacky. The Dahlquist criterion (Dahlquist, 1969) places that threshold at a storage modulus G' below 3 × 10^5 Pa at 25 °C and 1 Hz, the same threshold behind every permanently tacky grade among pressure-sensitive adhesives.
Antioxidants, Fillers and Other Additives#
Antioxidants protect a hot melt in the heated tank, at up to about 2 wt % of the formulation, with 0.25 to 1.0 wt % preferred in patent EP1976953B1. Antioxidant 1010 is used at 0.2 to 1 % in hot melt adhesives and 0.1 to 0.5 % in synthetic tackifier resins (typical product value, BASF Irganox 1010 data sheet, October 2022), basis not stated, while styrenic block copolymer hot melt pressure-sensitive adhesives take 0.3 to 0.5 wt % of formulation (Kraton, Adhesives and Sealants Industry, 2007).
A primary hindered phenol such as antioxidant 1010 pairs with a secondary phosphite such as antioxidant 168, and the two act together against oxidation in the tank, as in the APAO starting formula below with 0.5 and 1.0 wt %. Fillers such as chalk and barite set rheology and structure, not only cost, according to IVK.
Hot Melt Adhesive Formulation#
Hot melt formulation sets polymer, tackifier and wax shares in wt % of formulation: patent EP1976953B1 gives a 50 to 90 wt % copolymer blend in one embodiment, with tackifier and wax each up to 50 wt %. Every published range on this page carries its basis, and patent ranges describe what an inventor claimed, not what a formulator must use.
Composition Ranges by Hot Melt Type#
The table compares the published wt % shares of base polymer, tackifier, wax or oil and antioxidant for six hot melt types.
| Type | Base polymer (wt %) | Tackifier (wt %) | Wax or oil (wt %) | Antioxidant (wt %) | Source |
|---|---|---|---|---|---|
| EVA | ethylene copolymer (EVA in the examples) 40 to 85 | at most about 27 | synthetic wax 15 to 35 (Fischer-Tropsch in Example 6) | 0.1 to 2 | US20160230051A1 claims and description |
| Metallocene PO | 10 to 50 | rosin 10 to 30 or hydrocarbon 10 to 40 | paraffin 5 to 40 or Fischer-Tropsch 2 to 25 | 0.1 to 2 | EP3541887B1 |
| APAO | 55 or more (60 to 85) | not claimed; none in Example 2 | not claimed; Example 2 in the next table | 1.5 in Example 2 (0.5 + 1.0) | US20120328805A1 |
| HMPSA (SBC) | 43 (tape), 30 (elastic attachment) | midblock 52 (tape); 50 plus end-block 5 (elastic attachment) | oil 4 (tape), 15 (elastic attachment) | 1 (tape); 0.3 to 0.5 for SBC formulas | 2 examples of ExxonMobil/Dexco, ASI 2009; Kraton, ASI 2007 |
| Polyamide or copolyester | resin up to the whole adhesive | none | none | not stated | Bostik producer statement |
| Reactive PUR | NCO prepolymer, NCO/OH 1.5 | none | none | not stated; TPU modifier 10 to 15 | Carbonell Blasco et al. 2022; laboratory study 2024 (PMC11644545) |
Patent claim and example values, wt % of formulation; not recommendations.
Two rows differ in kind: polyamide and copolyester hot melts consist of the resin as delivered, and reactive PUR grades are built from an NCO prepolymer whose NCO/OH index, 1.5 in the Carbonell Blasco synthesis at 90 °C, matters more than any resin share. The 10 to 15 wt % thermoplastic polyurethane modifier is a 2024 laboratory result in which 10 wt % gave the best balance of green strength and flexibility.
Two Published Starting Formulas#
The table sets two complete published hot melt formulas side by side, one EVA case-and-carton type and one APAO type, with the results their patents report.
| Component or result | EVA type, US20160230051A1 Example 6 (H.B. Fuller), wt % | APAO type, US20120328805A1 Example 2 (H.B. Fuller), wt % |
|---|---|---|
| EVA, 18 % VA, melt index 500 | 50 | none |
| Resinall H-1030 tackifier | 19.5 | none |
| SHELLWAX SX 105 wax | 30 | none |
| REXtac RT 2304 APAO | none | 81.5 |
| Licocene 2602 | none | 5 |
| AC-596 | none | 5 |
| EPOLENE N-21 | none | 7 |
| Irganox 1010 (antioxidant 1010) | 0.5 | 0.5 |
| Irgafos 168 (antioxidant 168) | none | 1.0 |
| Sum | 100 | 100 |
| Viscosity, ASTM D3236 | 1,539 mPa·s (1,539 cP) at 177 °C, spindle 27 | 1,217 mPa·s (1,217 cP) at 176.7 °C |
| Set time | 1.3 s | 5.5 s |
| Cold fiber tear | 72 % at -29 °C (-20 °F) | 98 % at -28.9 °C (-20 °F) |
| Heat performance | heat stress 62.8 °C (145.0 °F), 0.91 kg (2 lb) cantilever load, 24 h | fiber tear 96 % at 60 °C (140 °F), 72 % at 65.6 °C (150 °F) |
The EVA formula comes from an application filed with priority 2015-02-06, published 2016-08-11 and since abandoned, so it describes a tested example, not a protected product. The trade-off between the two columns is set speed against heat: the EVA type sets faster, while the APAO type keeps more fiber tear in the cold.
Both viscosities are measured by ASTM D3236 at temperatures above the 175 °C (347 °F) upper limit of its scope, so both lie outside the method's stated range, and both formulas are patent examples, not recommendations.
How Each Component Moves Viscosity, Set Speed and Heat Resistance#
The table shows the direction in which raising each component's share moves a hot melt.
| Component | Raising its share | Source |
|---|---|---|
| Base polymer | more strength and flexibility | H.B. Fuller, 2024-08-29 |
| Vinyl acetate content in EVA | lower peak melting point: 91 °C at 14 % VA to 48 °C at 39 % VA | ExxonMobil Europe slate 2017, typical product values |
| Tackifying resin | better wetting and specific adhesion | H.B. Fuller, 2024-08-29 |
| Paraffin wax | lower viscosity, faster set | IGI producer statement; H.B. Fuller |
| Microcrystalline wax | more flexibility, temperature resistance and durability | IGI producer statement |
| Grafted wax (Licocene PP MA, 3 to 5 %, basis not stated) | adhesion to polar substrates | Clariant page, 2026-11-02 |
| Antioxidant | pot stability against char and viscosity drift | EP1976953B1 |
Read the table as one lever per problem: a bond that sets too slowly points to more paraffin, a bond that softens at heat points to microcrystalline wax or a lower-VA EVA, and a bond that fails on polar substrates points to a grafted wax.
Each request is passed straight to independent companies of that trade, and no company pays AdhesiveAdditives.com to be named or to receive requests; the editorial policy explains how.
Properties of Hot Melt Adhesives#
Hot melt adhesives are characterized in three states: in the melt by viscosity and melt flow, in transition by softening point, and in the solid by density and storage modulus G'. IVK lists melt viscosity in Pa·s from a rheometer, melt flow index in g/10 min and melt volume index in ml/10 min for the melt, softening point by Kofler bench or ring and ball for the transition, and density and storage modulus G' for the solid. Thermal stability and water resistance are not adhesive properties in this scheme: they belong to the bond system of adhesive plus substrates.
How Hot Melt Composition Sets Viscosity and Heat Resistance#
Hot melt viscosity is set by the melt index of the base polymer and by the wax share, and it is meaningful only with its temperature and method. ASTM D3236-15(2021) measures apparent viscosity up to 200,000 mPa·s at temperatures up to 175 °C (347 °F), and ASTM D1238-26 gives the melt index of EVA and polyethylene at 190 °C/2.16 kg.
Heat resistance of a thermoplastic hot melt follows the melting and softening of its polymer and resin. Softening point is measured by ring and ball under ASTM E28-18(2022), by its automated version ASTM D6493-11(2022), or by EN 1238, as cited by Carbonell Blasco et al. in Polymers (2022), who report 58 °C for their reference reactive hot melt.
Heat Resistance and Cold Flexibility#
Heat resistance after cure is the advantage of reactive PUR hot melts, and it is reported per grade. Henkel gives above 150 °C (302 °F) by its method of increasing temperature for TECHNOMELT PUR 4663 (data sheet September 2023) and PUR 3460 (October 2025), and above 120 °C for PUR 9720 (page read 2026-11-02), all typical product values.
Polyamide hot melts combine creep resistance at heat with flexibility in the cold. Henkel TECHNOMELT data sheets give temperature creep resistance by Henkel method MH 11 of 110 °C for PA 6238, 130 °C for PA 6208 N and 155 °C for PA 641 and PA 6790, and cold flexibility by ASTM D3111 of -10 °C, -40 °C, -35 °C and -20 °C for the same four grades (typical product values; PA 6208 N January 2018, PA 6790 June 2020, PA 6238 and PA 641 pages read 2026-11-02). ASTM D3111-19(2025) is an active mandrel bend practice.
Which Substrates Do Hot Melt Adhesives Bond?#
Hot melt adhesives bond 6 substrate groups: paper and board, wood and wood-based panels, plastics such as ABS, PVC and PET, textiles and nonwovens, metals, and leather. The six groups are listed below with the types that bond them.
- Paper and board: EVA and polyolefin types.
- Wood and wood-based panels: EVA, polyolefin and reactive PUR types.
- Plastics: ABS, PVC and PET; PE and PP after treatment.
- Textiles and nonwovens: polyolefin, pressure-sensitive and polyamide types.
- Metals: reactive PUR and polyamide types.
- Leather: polyamide and reactive PUR types.
Polyethylene (PE) and polypropylene (PP) are the exception among plastics, because IVK lists them as hot melt substrates only after treatment. Surface preparation for bonding these films and molded parts uses corona, plasma, flame or primers, as described under surface preparation for bonding.
Cold substrates shorten open time because they pull heat out of the bead faster, and Henkel lists flaking on cold substrates as a failure of PUR 9720 (page read 2026-11-02), whose data sheet asks for a substrate not below 20 °C.
Hot Melt Application Window#
Open time is the time after application during which the molten adhesive still wets the substrate, and setting time is the time until the joint is mechanically stable; both run from seconds to minutes. Both depend on heat flow into the substrate and the surrounding air. Hygiene spray lines show the short end: patent US8921474B2 describes open times below about 0.5 s at line speeds up to 213 m/min (700 ft/min). The test methods for open time and set speed are listed in the test table further down.
Melt temperature by chemistry, char prevention, setback and equipment belong to hot melt application, the process page shared by all five chemistries.
Forms of Delivery: Pellets, Blocks and Cartridges#
Hot melt adhesives are delivered as granules, pellets, blocks and cartridges, according to IVK. Reactive grades need moisture-tight packaging and dedicated melt units, because moisture that reaches the prepolymer starts skinning and gelling in the melter. Henkel's PUR 4663 (September 2023) and PUR 3460 (October 2025) data sheets call for airtight packaging and give a shelf life of 12 months, or 9 months for 2 kg containers. Polyamide pellets are kept in closed containers too, since absorbed moisture causes bubbles in the bead.
How Are Hot Melt Adhesives Tested?#
Hot melt adhesives are tested for melt viscosity, softening point, cold flexibility, heat resistance and set speed, and 3 ASTM hot melt methods (D4497, D4498, D4499) were withdrawn in 2021 but still appear on data sheets. The table lists each property with its standard, edition and status.
| Property | Standard and edition | Status | Method page |
|---|---|---|---|
| Melt viscosity | ASTM D3236-15(2021) | active, up to 175 °C (347 °F) | hot melt viscosity |
| Heat stability | ASTM D4499-07(2015) | withdrawn 2021, still cited on data sheets | covered on the viscosity page |
| Softening point | ASTM E28-18(2022), ASTM D6493-11(2022); EN 1238 as cited by Carbonell Blasco et al. 2022 | active (ASTM) | softening point testing |
| Open time | ASTM D4497-10(2018) | withdrawn 2021, still cited on data sheets | open time and set time |
| Heat-fail (SAFT, PAFT) | ASTM D4498-07(2015), as cited in EP3541887B1 | withdrawn 2021, still cited on data sheets | SAFT testing |
| Cold flexibility | ASTM D3111-19(2025) | active | no separate method page |
| Melt index | ASTM D1238-26 at 190 °C/2.16 kg | active | no separate method page |
| Wax properties | congealing point, drop melting point, needle penetration | named only | wax test methods for hot melts |
Set time in packaging patents follows a practical bead test: in EP3541887B1 a 2.0 g per linear meter bead is applied at 110 °C to corrugated board, and set time is the time to 100 % fiber tear, 1 to 3 s in its examples. The same patent bases its SAFT and PAFT heat-fail values on ASTM D4498, so a data sheet that cites D4498 today describes a method ASTM withdrew in 2021. Heat stability under the withdrawn ASTM D4499 reported viscosity change, skinning, Gardner color change and phase separation after conditioning at the recommended application temperature.
Regulation of Hot Melt Adhesives#
Three rule sets govern industrial hot melts: food-packaging listings such as 21 CFR 175.105, diisocyanate rules for reactive PUR grades, and VOC limits for adhesives. Thermoplastic hot melts are 100 % solids by producer statement, and VOC limits for industrial adhesives sit in rules such as SCAQMD Rule 1168 (amended November 4, 2022; amendments proposed for a 4 December 2026 hearing), covered under VOC limits for industrial adhesives. The hazard lines of the main raw materials, read at ECHA, are compared in the table below; rosin and 4,4'-methylene diphenyl diisocyanate (4,4'-MDI) are the two that carry a CLP Annex VI entry. Rosin (CAS 8050-09-7) carries CLP Annex VI 650-015-00-7 Skin Sens. 1 H317.
| Substance | CAS | Hazard line |
|---|---|---|
| Ethylene-vinyl acetate copolymer (EVA) | 24937-78-8 (ECHA list number 607-457-0) | No Annex VI entry |
| Hydrocarbon resins (petroleum resins) | 64742-16-1 (EC 265-116-8) | No Annex VI entry |
| Rosin | 8050-09-7 (EC 232-475-7) | Annex VI 650-015-00-7: Skin Sens. 1 H317 |
| Glycerol ester of rosin | 8050-31-5 (EC 232-482-5) | No Annex VI entry |
| 4,4'-MDI | 101-68-8 (EC 202-966-0) | Annex VI 615-005-00-9: H351, H332, H335, H373, H315, H319, H334, H317 |
Food-Packaging Hot Melts: 21 CFR 175.105 and EU Rules#
Hot melts for US food packaging use components listed in 21 CFR 175.105 under its conditions. The eCFR text (eCFR, up to date as of 2026-10-30) allows the adhesive behind a functional barrier, in contact with dry food within good manufacturing practice, or with fatty and aqueous food only as the trace amount at seams and at the edge exposure between packaging laminates. The finished adhesive container carries the label "food-packaging adhesive".
The list names polymers of ethylene and vinyl acetate, petroleum waxes and synthetic paraffin (Fischer-Tropsch) waxes, hydrocarbon resins, rosin and modified rosins, dimer-acid polyamides with listed amines, and polyurethane resins from diisocyanates and listed polyols. Ethylene-octene-1 copolymers qualify only with not less than 70 weight percent ethylene (CAS 26221-73-8), and the extractive limits of 21 CFR 177.1350 do not apply to EVA in 175.105 adhesives. No adhesive is cleared as such; in the US, 21 CFR 175.105 lists components and their conditions of use.
Food-contact adhesives in the EU fall under Regulation (EC) No 1935/2004, which lists adhesives as group 2 of Annex I among the materials that may be covered by specific measures; no specific EU measure covers adhesives as a whole. Good manufacturing practice under Regulation (EC) No 2023/2006 applies to all Annex I groups (Article 2), and migration testing is covered under food-contact adhesives.
Reactive PUR Hot Melts and Diisocyanate Rules#
Reactive PUR hot melts fall under REACH Annex XVII entry 74, added by Commission Regulation (EU) 2020/1149, when diisocyanates reach 0.1 % by weight or more, individually and in combination. Since 2023-08-24, industrial or professional use of such products requires documented training, renewed at least every five years, and since 2022-02-24 suppliers have placed a training statement on the packaging.
Mixtures that contain isocyanates, including monomers, oligomers and prepolymers, carry the supplemental statement EUH204, "Contains isocyanates. May produce an allergic reaction.", under CLP Annex II section 2.4 (Regulation (EC) No 1272/2008, consolidated text of 2026-07-01), unless the label already identifies them.
4,4'-MDI, the monomer of the prepolymer in the published synthesis cited above, carries CLP Annex VI entry 615-005-00-9 with eight hazard codes, among them Carc. 2 H351 and Resp. Sens. 1 H334, as listed in the hazard table. Training content for diisocyanates in adhesives is covered under diisocyanates in adhesives.
How to Choose a Hot Melt Adhesive#
Choose a hot melt by service temperature first, then by substrate, line speed and food-contact status. Service temperature separates thermoplastic from reactive types, substrate narrows the chemistry, line speed sets the required set time, and food contact limits the component list. The table pairs each requirement with a type and its evidence.
| Requirement | Hot melt type | Evidence |
|---|---|---|
| Fast case and carton sealing | EVA or APAO | set 1.3 s (EVA, US20160230051A1 Example 6) and 5.5 s (APAO, US20120328805A1 Example 2), patent examples |
| Low application temperature | metallocene PO | 121 °C or less claimed, as low as 107 °C (224.6 °F) described (EP3541887B1) |
| Permanent tack | HMPSA (SBC) | Dahlquist criterion: G' below 3 × 10^5 Pa at 25 °C and 1 Hz |
| Heat resistance after cure | reactive PUR | above 150 °C (TECHNOMELT PUR 4663, September 2023; PUR 3460, October 2025); above 120 °C (PUR 9720, page read 2026-11-02); Henkel data sheets |
| Textiles, electronics, higher service temperature | polyamide | creep resistance 110 °C (PA 6238), 130 °C (PA 6208 N, January 2018), 155 °C (PA 641; PA 6790, June 2020), Henkel method MH 11; PA 6238 and PA 641 pages read 2026-11-02 |
| Dry-food packaging in the US | any type built only from 175.105-listed components | conditions of use and the "food-packaging adhesive" label |
Each request is passed straight to independent companies of that trade, and no company pays AdhesiveAdditives.com to be named or to receive requests; the editorial policy explains how.
Limits of Hot Melt Adhesives#
Hot melt adhesives have 5 limits, listed below, that mark where a formula change or another chemistry takes over.
- Char and gel: overheating, oxidation and contamination degrade the melt in tank and hoses.
- Heat softening: thermoplastic grades soften again as service temperature nears the melting range of the polymer.
- Cold substrates: a cold surface shortens open time and causes flaking.
- Stringing: angel hair forms when the adhesive temperature is wrong for the nozzle.
- Moisture in polyamides: absorbed water causes bubbles in the bead.
For heat-resistant bonds, the reactive PUR and polyamide types in the comparison table below are the hot melt answer.
Types of Hot Melt Adhesive: Sub-Chemistries Compared#
Hot melt adhesives come in 5 chemistries and 1 process discipline: EVA, polyolefin, hot melt pressure-sensitive, polyamide and polyester, and reactive polyurethane, plus the application know-how all of them share. The table compares base polymer, application temperature, set or cure and main uses for each type.
| Type | Base polymer | Application temperature | Set or cure | Main uses |
|---|---|---|---|---|
| EVA hot melt adhesives | EVA with tackifier and wax | about 177 °C (350 °F) conventional | physical, seconds; set 1.3 s in a patent example | case and carton, bookbinding, wood |
| Polyolefin hot melts | APAO, metallocene PO, OBC | about 177 °C conventional; low-temperature metallocene PO 121 °C or less, as low as 107 °C (224.6 °F) | physical; 1 to 3 s (EP3541887B1 examples); 5.5 s (APAO, US20120328805A1 Example 2) | packaging, hygiene, edgebanding |
| Hot melt pressure-sensitive adhesives | SBC, APAO, metallocene PO with oil and tackifier | set by the formula (no single range in the source) | permanently tacky | labels, tapes, hygiene |
| Polyamide and polyester hot melt adhesives | dimer-acid PA, copolyamide (CoPA), copolyester (CoPES) | 180 to 240 °C across Henkel TECHNOMELT PA 6208 N (January 2018), 6238, 641 (pages read 2026-11-02) and 6790 (June 2020) | physical | electronics low-pressure molding, textiles, footwear, assembly |
| Reactive polyurethane hot melts | NCO prepolymer (PUR); silane-grafted APAO (POR) | 100 to 140 °C (PUR 4663, September 2023), 110 to 140 °C (PUR 3460, October 2025), 110 to 150 °C (PUR 9720, page read 2026-11-02), Henkel data sheets | green strength, then moisture cure in 2 to 5 days (PUR 4663, 3460) or 3 to 7 days (PUR 9720) | wood, automotive interiors, textiles, bookbinding |
| Hot melt application (process row) | all types | 121 to 204 °C (250 to 400 °F) typical (Henkel) | process settings | melt temperature, open time, equipment, char |
Set behavior separates the types as sharply as temperature does: seconds for EVA and polyolefins, days of moisture cure for reactive PUR, so a line that needs handling strength at once and heat resistance later takes a reactive grade.
Hot Melt Adhesives in Industry and Research#
Industrial hot melts serve packaging, hygiene and bookbinding first, and current research targets compostable base polymers. They sit next to water-based, solvent-based, reactive and pressure-sensitive systems among all types of adhesives by chemistry, and the three questions below cover where industrial hot melts are used, what a supplier data sheet must state and how the technology developed.
Where Are Industrial Hot Melt Adhesives Used?#
Industrial hot melt adhesives serve 3 main application fields, listed below with the hot melt types each uses.
- Packaging adhesives: packaging hot melt adhesive for case and carton sealing, built on EVA and polyolefin types.
- Hygiene adhesives: spray-applied pressure-sensitive and polyolefin hot melts for nonwovens and elastic strands, with open times below about 0.5 s.
- Bookbinding adhesives: EVA and reactive PUR hot melts.
Wood and edgebanding, automotive interiors, textiles, footwear and electronics low-pressure molding use hot melts as well, through the EVA, polyolefin, polyamide and reactive types in the comparison table.
What Should a Hot Melt Adhesive Supplier State on the Data Sheet?#
A hot melt adhesive supplier should state every data sheet value as a typical product value with its temperature and test method. A heat-fail value cited to ASTM D4498 refers to a method withdrawn in 2021. The six fields below make two data sheets comparable.
- Viscosity, with temperature, spindle and method.
- Softening point, with its method (ASTM E28, ASTM D6493 or EN 1238).
- Application temperature range.
- Open time and set time, with the test conditions.
- Heat resistance, with method and load.
- Regulatory statements, such as 21 CFR 175.105 status with its conditions of use and entry 74 training information for reactive grades.
Comparing adhesive manufacturers and suppliers on these same fields keeps the choice on measured values; sourcing and qualification steps are covered under adhesive manufacturers and suppliers.
From 1940 to Compostable Hot Melts#
Hot melt adhesives were introduced in 1940 to replace water-based adhesives that failed in humid climates, according to H.B. Fuller (producer claim, 2024-08-29).
Current research targets compostable hot melts. A 2026 packaging review (PMC13468549) covers polylactic acid (PLA), polybutylene succinate (PBS), polybutylene adipate terephthalate (PBAT) and polyhydroxyalkanoates (PHA) as base polymers, and reports that a PBAT and rosin maleic resin blend at 30 wt % reached about 7.3 MPa shear strength against 3.9 MPa for an EVA reference, laboratory values rather than data sheet values.