JPS6223795B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a base composition for hot melt preparations. More specifically, the present invention relates to a base composition for hot melt agents that can be crosslinked by contacting with water in the presence of a silanol catalyst. In general, a hot melt composition is a solid state at room temperature made by blending a base resin such as ethylene-vinyl acetate copolymer with a tackifier resin and/or wax, and if necessary, a plasticizer, pigment, filler, etc. It is used after being melted by heating and solidified by cooling. Taking advantage of its advantages, this hot melt composition can be used in many fields such as adhesives, coating agents, pressure sensitive adhesives, sealants, and paints such as traffic paint. has been done. Among these, hot melt adhesives have been recognized for their advantages, such as being able to bond in a short time (high speed) and being non-polluting, and their growth has been attracting attention in recent years. These hot melt compositions generally have a base resin that provides cohesive force and adhesive strength as an essential main component, a tackifier resin and/or wax that provides tackiness, and optional components such as a plasticizer, antioxidant, and filler. The base resin, which is the main component of the hot melt composition, includes ethylene-vinyl acetate copolymer, low-density polyethylene, ethylene-α-olefin copolymer,
Since polyamide resins and other resins are all thermoplastic resins, their biggest drawback is their poor heat resistance. Currently, the hot melt compositions are mainly used as adhesives and coating agents, but they can also be used to create new products such as labels, adhesives for tapes, product assemblies, sealants, and shoe making. Efforts are being made to expand its use. However, as mentioned above, the composition itself lacks heat resistance, which currently hinders the development of these new uses. Various attempts have been made to improve the heat resistance of hot melt compositions. For example, in order to improve heat resistance, it is conceivable not to include tackifying resins and wax components, which are important components of hot melts. However, when a hot melt composition is used as an adhesive, the tackiness will be significantly reduced unless a tackifier is added, and when used as a coating agent, omitting the wax will increase the viscosity and reduce the wettability. In practice, it is essentially difficult to omit these components from hot melt compositions, and therefore, in order to improve heat resistance, it is necessary to improve the thermoplastic resin itself, which is the base resin. Examples of ways to improve thermoplastic resins include polyamide resins, which have better heat resistance than ethylene-vinyl acetate copolymers, which are the base resins that have been overwhelmingly used in the past;
Methods using polyester resins and styrene-butadiene (isoprene)-styrene block copolymers have been proposed. However, although these methods improve heat resistance slightly, they are still not satisfactory; on the contrary, the compatibility between the base resin and the tackifier resin or wax becomes poor, and the tackiness of the hot melt composition increases. New drawbacks arise. Another method is to crosslink a base resin such as ethylene-vinyl acetate copolymer with an organic peroxide, but this method causes a significant increase in the viscosity of the composition when mixing the components, and it causes damage to the base material. There is a risk that application will be difficult. As described above, it has been extremely difficult to improve the heat resistance of existing hot melt compositions without impairing their physical properties. The inventors of the present invention solved this problem, and as a result of intensive research in order to significantly improve the heat resistance of hot melt compositions that use existing polyolefin resins as a base resin without impairing their excellent physical properties.
It has been found that a base composition for hot melt agents having a silane compound-modified polyolefin as the base resin can effectively solve this problem. Therefore, the present invention relates to a base composition for a hot melt agent, which is made by mixing a silane compound-modified polyolefin with a tackifying resin and/or a wax, in which a silane-modified product is used. Therefore, crosslinking is possible by contacting with water in the presence of a silanol catalyst. Specifically, the silane compound-modified polyolefin used in the present invention includes silane compound-modified polyethylene, silane compound-modified ethylene-unsaturated ester copolymer, silane compound-modified ethylene-α-olefin copolymer, and silane compound-modified ethylene-α-olefin copolymer. Examples include -olefin-diolefin copolymers and mixtures of two or more thereof, and among these, silane compound-modified ethylene-vinyl acetate copolymers are particularly preferred as silane compound-modified polyolefins. In addition, these silane compound-modified polyolefins can be produced by (i) a method in which a polyolefin is subjected to a graft reaction with a silane compound in the presence of a free radical-generating compound (Japanese Patent Publication No. 50-35940, Japanese Patent Application Laid-Open No. 150594/1989), or (ii) A method of radical copolymerizing a mixture of an olefin monomer and an unsaturated silane compound under high pressure in the presence of a polymerization initiator and a chain transfer agent.
No. 50-91039). To explain the former silane modification method in more detail, the raw polyolefins used for silane modification in this method include polyethylene, ethylene-unsaturated ester copolymers such as ethylene-vinyl acetate copolymer, and ethylene-acrylic acid ester copolymer. ethylene-α-olefin copolymers such as ethylene-propylene copolymers, ethylene-butene-1 copolymers, ethylene-α-olefin-diolefin copolymers such as ethylene-propylene-dicyclopentadiene copolymers; Examples include combinations and mixtures of two or more of these, and among these, ethylene-vinyl acetate copolymers having a vinyl acetate content of 5 to 50% by weight are particularly preferred. The silane compound to be reacted with the polyolefin is represented by the general formula _RR'SiY2 , where R is an unsaturated hydrocarbon group such as a vinyl group, allyl group, butenyl group, or cyclohexenyl group, or a hydrocarbon oxy group. represents a group, and Y is an alkoxy group such as a methoxy group or an ethoxy group,
For example, it is any hydrolyzable organic group such as a formyloxy group, an acyloxy group such as an acetoxy group, an oxime group, and R' is, for example, methyl, ethyl,
It can be a monovalent hydrocarbon group or group R or group Y that does not contain fatty unsaturation, such as propyl, phenyl, benzyl, tolyl, and the like. In particular, it is preferred that the silane compound contains three hydrolyzable organic groups, with the most preferred silane compounds being vinyltriethoxysilane and vinyltrimethoxysilane. The proportion of silane compounds used depends on the reaction conditions and degree of modification, but usually
0.1 to 30% by weight, preferably 0.5 to 10% by weight
It is preferable to use Examples of free radical generating compounds include organic peroxides and peresters such as benzoyl peroxide,
Dichlorobenzoyl peroxide, dicumyl peroxide, di-tert-butyl peroxide, 2,5-
di(peroxybenzoate)hexyne-3,
1,3-bis(tert-butyl-peroxyisopropyl)benzene, lauroyl peroxide, tert-butyl peracetate, 2,5-dimethyl-2,5
-di(tert-butylperoxy)hexyne-3,
2,5-dimethyl-2,5-di(tert-butylperoxy)hexane and tert-butyl peroxybenzoate, tert-butyl peroxyoctoate,
Mention may be made of azo compounds such as azobis-isobutyronitrile and dimethylazodiisobutyrate, with tert-butyl peroxyoctoate being most preferred. Further, it is usually preferable to use the organic radical-forming compound in an amount of 0.05 to 2.0% by weight based on the polyolefin. To silane-modify a polyolefin, the polyolefin, the above-mentioned silane compound, and a free radical generating compound are mixed in any device and heated at any temperature between 80°C or higher and the decomposition temperature of the polyolefin, preferably 100 to 160°C. React with.
A suitable reaction time is 2 to 10 minutes. Although any reactor can be used, it is usually preferable to use an extruder, a Banbury mixer, a roll mill, or the like. In addition, to explain the latter silane modification method, in this method one or more monomers of α-olefins such as ethylene, propylene, butene, olefins such as vinyl acetate and methyl acrylate and an unsaturated silane compound are used. The mixture is subjected to radical polymerization in the presence of the above-mentioned organic peroxide at a temperature of 40 to 300°C and a pressure of 700 to 3000 Kg/cm ² , and at the same time a crosslinking reaction is carried out. A particularly preferred olefin monomer is a mixture of ethylene and vinyl acetate, and the unsaturated silane compound has a copolymerizable double bond in the molecule and a functional group containing a crosslinkable silane. compound is used. Among these, vinyltriethoxysilane is particularly preferred. The above unsaturated silane compound is 0.1 to polyolefin.
It is added in an amount of 3% by weight, preferably 0.1 to 1.5% by weight. In the present invention, among the above two types of silane modification methods,
It is more preferable to use the former silane modification method, that is, a method in which a polyolefin is graft-reacted with a silane compound in the presence of a free radical-generating compound, from the viewpoint of crosslinking properties of the obtained silane compound-modified polyolefin. Silane compound-modified polyolefins have the advantage that there is no decrease in melt index that occurs when polyolefins are crosslinked with organic peroxides, and they are well compatible with tackifying resins and waxes when melt-mixed, just like normal base resins. ing. In the present invention, at least one of a tackifying resin and a wax is blended with the above-mentioned silane compound-modified polyolefin. The tackifying resin used in the present invention includes rosin resins such as rosin, rosin ester, hydrogenated rosin, terpene resins, terpene-phenol resins, coumaron-indene resins, aliphatic petroleum resins, aromatic petroleum resins, and Examples include partially hydrogenated products thereof, aromatic-aliphatic copolymerized petroleum resins ( _C9 - _C5 petroleum resins), and alicyclic petroleum resins. Waxes used in the present invention include petroleum waxes such as paraffin wax and microwax, natural waxes such as wood wax, carnauba wax, and beeswax, crystalline polyethylene wax, crystalline polypropylene wax, and atactic polypropylene. Among these, paraffin wax, microcrystalline wax and polyethylene wax with a softening point of 40 to 100°C are preferred. Furthermore, in the composition of the present invention, the blending ratio of the silane compound-modified polyolefin, which is the base resin, and the tackifier resin and/or wax varies depending on the application. For agent applications, the following blending ratios are preferred. [For hot melt adhesives] Silane compound-modified polyolefin 10-60% by weight Tackifier resin 10-60% by weight Wax 0-50% by weight [For hot-melt coating agents] Silane compound-modified polyolefin 0.5-10% by weight Wax 99.5-90% by weight % To prepare a base composition for a hot melt agent, the above-mentioned components are heated and melted at 100 to 200°C, preferably 140 to 180°C, and thoroughly stirred to obtain a homogeneous mixture. As a means for heating and melting and mixing, any device that can perform heating and mixing may be used. In addition to the above-mentioned components, the base composition for hot melt agents of the present invention may optionally contain additives such as plasticizers such as dioctyl phthalate and dibutyl phthalate, antioxidants, fillers such as calcium carbonate, and pigments. May be added. The heated and molten homogeneous mixture is cooled and formed into granules, flakes, pellets, rods, etc. depending on the purpose. The base composition for a hot melt agent thus obtained is brought into contact with water in the presence of a silanol catalyst and crosslinked, thereby forming a hot melt agent with extremely excellent heat resistance. When using a hot melt composition, the silanol catalyst is added when the composition is heated and melted again, and the hot melt composition to which the silanol catalyst has been added is stirred for 20 to 30 minutes and then applied to the surface of the adherend. In this case, by adding a silanol catalyst to the silane compound-modified polyolefin itself, crosslinking will proceed sufficiently even in the presence of moisture in the air, but when melt-mixing as a hot melt compound, a silanol condensation catalyst is added. After 3 hours, the melt viscosity did not change at all and remained stable. Therefore, it is possible to use the manufacturing method and coating method that have been used up to now without any changes. When the base composition for hot melt agents of the present invention is mixed with a silanol catalyst immediately before use and used for hot melt agent applications such as hot melt adhesives and hot melt coating agents, the silane compound-modified polyolefin is stored alone and used. Compared to the case where tackifier resin and/or wax and silanol catalyst are added immediately before use,
The following advantages can be seen. (1) In the base composition of the present invention, the silane active sites of the silane compound-modified polyolefin are diluted with the tackifying resin and/or wax, so that undesirable silane crosslinking reactions due to moisture in the atmosphere occur during storage. This results in decreased formability in adhesives and coating applications (failures such as clogging of the coating device outlet due to cross-linked materials during coating work) and decreased performance (because of cross-linked materials, if applied thinly, the coating film may deteriorate). It is possible to prevent problems such as cutting of the coating film, bumps on the coating film, and failure to obtain a smooth film. (2) Since the base composition of the present invention already has a tackifying resin and/or wax mixed with the silane compound-modified polyolefin and is supplied to the user in the form of such a mixture, there is no possibility of defective adhesion on equipment surfaces. The work of mixing these agents, coating agents, etc. at the application site can be omitted, which not only shortens and simplifies the work time, but also reduces undesirable crosslinking reactions caused by moisture in the atmosphere during the mixing work. These workability problems can also be solved by using a hot melt composition in which a tackifying resin and/or wax and a silanol catalyst are added to a silane compound-modified polyolefin, but in this case, during storage of the hot melt composition, There is a high possibility that a silane crosslinking reaction will occur in the product, resulting in the aforementioned deterioration in moldability and performance, so care must be taken to store it in a dry state to avoid contact with moisture such as atmospheric humidity. However, with the base composition for hot melt agents of the present invention, there is no need to take such special considerations. Examples of silanol condensation catalysts include dibutyltin dilaurate, stannous acetate, stannous octoate (stannous caprylate), lead naphthenate, zinc caprylate, iron 2-ethylhexanoate, and cobalt naphthenate. Organometallic compounds such as carboxylates, titanate esters and chelates such as titanate tetrabutyl ester, titanate tetranonyl ester and bis(acetylacetonitrile) di-isopropyltitanate, organic bases such as ethylamine, hexylamine, dibutylamine and Mention may be made of pyridine, acids such as inorganic acids and fatty acids. Suitable catalysts are organotin compounds such as dibutyltin dilaurate, dibutyltin diacetate and dibutyltin dioctoate. There is no particular limit to the amount of silanol catalyst added, but
0.001 to 1 for normal silane-modified polyolefin
Weight percent is preferred. The silanol condensation catalyst may be added directly to the base composition, but for ease of handling, it is also effective to mix it with a small amount of wax or tackifying resin in advance and then add it. If the crosslinking speed after coating is to be carried out using moisture in the air, there will be some differences depending on the relative humidity, but the crosslinking will proceed within a range that poses no practical problem. If you want to complete crosslinking more quickly, you can do it extremely quickly by applying steam or spraying water to bring it into contact with moisture. The crosslink density is basically adjusted by the grafting ratio, but it can also be adjusted by the amount of the silanol condensation catalyst. The base composition for hot melt agents of the present invention does not change its melt viscosity at all from its manufacture to its application to the adherend, and crosslinking progresses even with moisture in the air after it is applied. Since it does not require a complicated crosslinking process, it can be used in exactly the same way as conventional hot melt compositions.
Moreover, it is possible to obtain a hot melt agent with extremely good heat resistance, and in this respect the present invention is truly revolutionary. The base composition for hot-melt agents of the present invention has excellent physical properties, especially heat resistance, as described above, so it can be used not only in conventional fields of use such as adhesives and coating agents, but also in areas where heat resistance is required. It is also used for labels, tape adhesives, product assemblies, sealants, etc. EXAMPLES Next, the present invention will be explained in more detail with reference to Examples, but the present invention is not limited to these Examples. In addition, in the following examples, the physical properties of the base composition for hot melt agents were measured by the following method. (1) Melt viscosity of the obtained hot melt adhesive composition at 160℃
The melt viscosity was measured using a B-type rotational viscometer. (2) Softening point The hot melt adhesive composition was heated at 30°C for 3 hours.
Measurements were made using the ring and ball method (based on JIS K 2351) for those subjected to contact treatment with hot water. (3) Tensile strength at break, elongation at break The hot melt adhesive composition was heated at 30°C for 3 hours.
For those that have been contact treated with hot water,
Measured according to ASTMD-882. Example 1 Vinyl acetate content 28% by weight, melt index
150 ethylene-vinyl acetate copolymer (manufactured by Mitsui Polychemical Co., Ltd., trade name: Evaflex #220)
A solution prepared by dissolving 0.3 parts by weight of t-butylperoxyoctoate in 5.0 parts by weight of vinyltrimethoxysilane was sprinkled onto the surface of 100 parts by weight of the pellets until completely dispersed. Next, this pellet was kneaded for 5 minutes at 140 DEG C. in a double-arm kneader to obtain a silane grafted product of ethylene-vinyl acetate copolymer (hereinafter referred to as EVA #220 silane grafted product). Next, 40 parts by weight of this EVA#220 silane graft was melted in advance in a beaker in an oil bath set at 160°C to paraffin wax (manufactured by Nippon Seiro Co., Ltd., product name 145). ) and 40 parts by weight of glycerin ester of hydrogenated rosin (manufactured by Arakawa Chemical Co., Ltd., trade name: Ester Gum H) and stirred and mixed for about 1 hour to form a base composition for hot melt agents. Obtained. After the stirring was completed, dibutyltin dilaurate was newly added to this base composition at a ratio of 500 ppm to the EVA silane grafted material, and the mixture was stirred for about 10 minutes to obtain a hot melt adhesive composition. The physical properties of this composition were measured and the results are shown in Table-1. Comparative Example 1 Instead of EVA #220 silane grafted material used in Example 1 as the base resin, non-silane modified vinyl acetate content 28% by weight, melt index 150
A hot melt adhesive composition was obtained in exactly the same manner as in Example 1, except that an ethylene-vinyl acetate copolymer (manufactured by Mitsui Polychemical Co., Ltd., trade name: Evaflex #220) was used. The physical properties of this composition were measured and the results are shown in Table-1.

[Table] Example 2 Vinyl acetate content 33% by weight, melt index
30 ethylene-vinyl acetate copolymer (manufactured by Mitsui Polychemical Co., Ltd., trade name: Evaflex #150) was silane-modified under the same conditions as in Example 1 to obtain an ethylene-vinyl acetate silane grafted product (hereinafter referred to as EVA).
#150 silane grafted product) was obtained. Next, add 40 parts by weight of this EVA #150 silane graft to 160 parts by weight.
40 parts by weight of aromatic petroleum resin (manufactured by Mitsui Petrochemical Industries, Ltd., trade name Petrosine #100), which had been melted in advance in a beaker in an oil bath set at ℃;
The mixture was added to a mixture with 20 parts by weight of paraffin wax (145% paraffin wax manufactured by Nippon Seiro Co., Ltd.) and stirred and mixed for about 1 hour to obtain a base composition for a hot melt agent. After the stirring was completed, dibutyltin dilaurate was newly added to this base composition at a ratio of 500 ppm to the EVA #150 silane grafted product, and stirred for about 10 minutes to obtain a hot melt adhesive composition. The physical properties of this composition were measured and the results are shown.
Shown in 2. Comparative Example 2 Instead of the silane-grafted product of EVA#150 used in Example 2 as the basic resin, an ethylene-vinyl acetate copolymer (Mitsui Polychemical Co., Ltd.) with a non-silane modified vinyl acetate content of 33% and a melt index of 30 was used. A hot melt adhesive composition was obtained in exactly the same manner as in Example 2, except that EVAFLEX #150 (trade name, manufactured by Co., Ltd.) was used. The physical properties of this composition were measured and the results are shown in Table 2.

【table】

[Table] Example 3 40 weight pieces of the same ethylene-vinyl acetate copolymer silane grafted product (EVA #220 silane grafted product) used in Example 1 were placed in a beaker in an oil bath set at 160°C. Pre-melted paraffin wax (manufactured by Nippon Seiro Co., Ltd., product name 145)
20 parts by weight of paraffin wax) and 40 parts by weight of β-pinene polymer (manufactured by Yasushi Oil Industries Co., Ltd., trade name YS Resin), stirred and mixed for about 1 hour, and prepared as a hot melt agent. A base composition was obtained. After the stirring was completed, dibutyltin dilaurate was newly added to this base composition at a ratio of 500 ppm based on the EVA silane graft, and stirred for about 10 minutes to obtain a hot melt adhesive composition. The physical properties of this composition were measured and the results are shown in Table 3. Comparative Example 3 In place of the EVA #220 silane grafted material used in Example 3 as the base resin, a non-silane modified vinyl acetate content of 28% by weight and a melt index of 150 were used.
A hot melt adhesive composition was obtained in exactly the same manner as in Example 3, except that an ethylene-vinyl acetate copolymer (manufactured by Mitsui Polychemical Co., Ltd., trade name: Evaflex #220) was used. The physical properties of this composition were measured and the results are shown in Table 3.

【table】

[Table] Example 4 Low-density polyethylene with a melt index of 400 and a density of 0.910 g/cm ³ was silane-modified under the same conditions as in Example 1 to obtain a silane-grafted polyethylene. Next, this polyethylene silane graft material 40
20 parts by weight of paraffin wax [manufactured by Nippon Seiro Co., Ltd., product name 145] paraffin wax, which had been melted in advance in a beaker in an oil bath set at 160°C, and hydrogenated petroleum resin. [Manufactured by Arakawa Chemical Co., Ltd.]
The mixture was added to a mixture with 40 parts by weight of Alcon P-100 (trade name) and stirred and mixed for about 1 hour to obtain a base composition for hot melt. After the stirring was completed, dibutyltin dilaurate was newly added to the base composition at a ratio of 500 ppm to the polyethylene silane graft,
A hot melt adhesive composition was obtained by stirring for about 10 minutes, the physical properties of this composition were measured, and the results are shown in the table.
4. Comparative Example 4 In place of the polyethylene silane grafted material as the base resin in Example 4, low density polyethylene (melt index
A hot melt adhesive composition was obtained in exactly the same manner as in Example 4, except that 400 g/cm 3 (density 0.910 g/cm ³ ) was used. The physical properties of this composition were measured and the results are shown in Table 4.

[Table] Example 5 Ethylene-propylene-diene terpolymer [manufactured by Mitsui Petrochemical Industries, Ltd., trade name: Mitsui EPT]
#4021] was subjected to silane modification under the same conditions as in Example 1 to obtain an ethylene-α-olefin copolymer silane graft product. 10 parts by weight of this ethylene-α-olefin copolymer silane grafted product and 30 parts by weight of the same ethylene-vinyl acetate copolymer silane grafted product (EVA #220 silane grafted product) used in Example 1, Paraffin wax pre-melted in a beaker in an oil bath set at 160℃ [145〓Paraffin wax Japanese wax
Co., Ltd.] and 40 parts by weight of an aromatic petroleum resin (trade name: Picobar AP-25, manufactured by Hercules Co., Ltd.), and stirred and mixed for about 1 hour to form a base composition for hot melt agents. Obtained. After stirring, add dibutyltin dilaurate to the composition.
Added to this base composition at a rate of 200 ppm, approx.
A hot melt adhesive composition was obtained by stirring for 10 minutes, and the physical properties of this composition were measured, and the results are shown in Table 5. Comparative Example 5 In Example 5, 10 parts by weight of silane grafted ethylene-α-olefin copolymer and 30 parts by weight of silane grafted ethylene-vinyl acetate copolymer were used as the base resin.
10 parts by weight of a non-silane-modified ethylene-α-olefin copolymer [manufactured by Mitsui Petrochemical Industries, Ltd., trade name Mitsui EPT #4021] and 10 parts by weight of non-silane-modified ethylene-α-olefin copolymer A hot melt adhesive composition was obtained in exactly the same manner as in Example 5, except that a mixture of 30 parts by weight of vinyl acetate copolymer (manufactured by Mitsui Polychemical Co., Ltd., trade name: Evaflex #220) was used. Table 5 shows the results of measuring the physical properties of this composition.

【table】

【table】

【table】

Claims (1)

[Scope of Claims] 1. A base composition for a hot melt agent, which is made of a mixture of a silane compound-modified polyolefin and a tackifying resin and/or a wax, and which becomes crosslinkable when a silanol catalyst is added to the mixture and brought into contact with water. thing. 2. Claims, page 1, in which the silane compound-modified polyolefin is a silane-modified product of polyethylene, an ethylene-unsaturated ester copolymer, an ethylene-α-olefin copolymer, or an ethylene-α-olefin-diolefin copolymer. The base composition for hot melt preparations described above. 3. The base for a hot melt agent according to page 2 of the claims, wherein the silane compound-modified ethylene-unsaturated ester copolymer is a silane-modified product of an ethylene-vinyl acetate copolymer having a vinyl acetate content of 5 to 50% by weight. Composition.