JPH08109360A - Hot-melt adhesive - Google Patents

Abstract

PURPOSE: To obtain a hot-melt adhesive, transparent in a melt state and opaque at normal temperatures, containing a specific amorphous polyolefin and a tackifier and capable of reducing the bleeding to especially a moisture-permeable olefinic resin film and good in coating performances. CONSTITUTION: This adhesive contains (A) an amorphous polyolefin, having 1000-20000 number-average molecular weight and containing >=20wt.% propylene component and (B) a tackifier (e.g. natural rosin). The >=40 value of L which is a measured value with a color-difference meter. Although, e.g. polypropylene or a propylene-ethylene copolymer can be used as the component (A), a polyolefin having <=15wt.% content of a portion insoluble in boiling n-heptane with a Soxhlet extractor is preferred. The amount of he blended component (B) is preferably 70-20wt.%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hot melt adhesive which is particularly suitable for adhering a moisture-permeable olefin resin film and has less bleeding to the film.

[0002]

2. Description of the Related Art A moisture-permeable olefin resin film used for sanitary materials such as disposable paper diapers is porous so that the user does not get it. A rubber-based adhesive often used for this purpose uses a styrene-based thermoplastic elastomer as a base polymer. Its molecular weight is generally 70,000-100,000
Therefore, when compounding an adhesive, low molecular weight compounds such as oil, liquid polybutene, and wax are compounded for the purpose of improving coating performance. Therefore, such a low molecular weight compound has a drawback that it easily exudes from the fine pores of the moisture-permeable olefin resin film.

[0003]

In order to solve this problem, the use of an amorphous propylene / ethylene random copolymer as a base polymer is disclosed in JP-A-1-26617.
No. 5, JP-A-3-115483, JP-A-5-
No. 148465 and Japanese Patent Laid-Open No. 5-228172. The amorphous polyolefin adhesives disclosed in the above patents have low melt viscosity
It is not necessary to mix a large amount of low molecular weight substances such as liquid polybutene and wax, and the bleeding into the moisture-permeable olefin resin film is improved compared to rubber adhesives. However, yearly disposable diapers have a tendency to thin the moisture-permeable olefin resin film in order to improve the user's comfort and moisture permeability. Therefore, even if an adhesive with improved bleeding is used, bleeding is noticeable, and therefore an adhesive with improved bleeding is desired. Therefore, an object of the present invention is to provide a hot-melt adhesive that has almost no bleeding of the moisture-permeable olefin resin film, has excellent adhesive performance, and has little difference in color tone from the moisture-permeable olefin resin film.

[0004]

The hot melt adhesive of the present invention contains an amorphous polyolefin having a number average molecular weight of 1,000 to 20,000 and a propylene component of 20% by weight or more, and a tackifier. The object is achieved by providing a hot-melt adhesive which is transparent in a molten state and opaque at room temperature.

The present invention will be described in more detail below. The present inventor has studied amorphous polyolefins and tackifiers, and as a result, when an adhesive is transparent when melted, it may be transparent or opaque when solidified, and opaque when melted. In the case of, it was found to remain opaque even after solidification. Adhesives that are opaque when melted have extremely poor compatibility between the materials that are mixed during the coating operation, and therefore the adhesives are prone to phase separation and are easily deteriorated by heat, which reduces melt viscosity and peel strength. It is difficult to use as an adhesive because of problems such as deterioration of physical properties such as deterioration of nozzles and nozzle clogging due to skin generation. On the other hand, an adhesive that is transparent when melted can be used without the above problems. The present invention is a hot melt adhesive that is transparent when melted and becomes opaque when solidified.

On the other hand, the moisture-permeable olefin resin film is white, and when the transparent adhesive oozes out on this film when it solidifies, the bleeding portion becomes transparent, and the light and dark areas are clear. The bleeding portion is conspicuous and the commercial value decreases. Further, even if the opaque adhesive oozes out during solidification, the adhesive itself is opaque, so that it is difficult to understand the contrast between the bleeding portion and the non-bleeding portion. The amorphous polyolefin and the tackifier are appropriately selected in the hot melt adhesive of the present invention, and are blended in consideration of transparency in a molten state and opacity at room temperature. Further, when the adhesive of the present invention is applied to a moisture-permeable olefin resin film, it is preferable that the bleeding-out value measured by a color difference meter (L value) is 8 or more.

The amorphous polyolefin used in the present invention may be atactic polypropylene produced as a by-product during the production of crystalline polypropylene, or may be produced by copolymerizing propylene with other α-olefins. Other copolymers can be used.

In the case of producing amorphous polypropylene, it is possible to use, for example, a polymer obtained in the presence of hydrogen using a titanium-supported catalyst supported on magnesium chloride and triethylaluminum. From the viewpoint of supply stability and quality stability, it is preferable to use the objectively produced amorphous polyolefin. Specifically, polypropylene, propylene / ethylene copolymer, propylene / butene-1 copolymer, propylene / ethylene / butene-1 terpolymer, propylene and hexene-1, octyne-1.
Alternatively, an amorphous polyolefin containing propylene as a main component such as a copolymer with 2-methylpentene-1 can be used.
Of these, the propylene / ethylene copolymer has an ethylene content of 0 to 30% by weight, and preferably,
It is 1 to 20% by weight. When the ethylene content is more than 30% by weight, it becomes too soft and the surface tackiness is too large to be used as an adhesive.

Regarding the propylene / butene-1 copolymer, the butene-1 content is 0 to 80% by weight, preferably 5 to 70% by weight. If the butene-1 content is more than 80% by weight, the softening point becomes too low. Further, the above polyolefin has a number average molecular weight of 1,000 to
It is 20,000, preferably 1,500 to 15,000. When the number average molecular weight is less than 1,000, the cohesive force is too low to be practical. On the other hand, if it exceeds 20,000, the viscosity at the time of melting becomes too high, which makes application difficult.

Further, the polyolefin of the present invention has a Soxhlet extraction insoluble content by boiling n-heptane of 40% by weight or less, preferably 20% by weight or less, more preferably 15% by weight or less. The amorphous polyolefin of the present invention preferably has almost no endothermic peak at the time of crystal melting in the temperature rise measurement of the differential scanning calorimeter. In the amorphous polyolefin of the present invention,
If the boiling n-heptane insoluble content is higher than the above range, or if the heat of crystal fusion is large, when used as an adhesive, the open time is too short, the meat becomes thin after application, and the adhesive strength changes over time. Is not preferred.

Examples of the tackifier used in the present invention include natural rosin (gum rosin, wot rosin, tall oil rosin, etc.), modified rosin (polymerized rosin, hydrogenated rosin, etc.), coumarone / indene resin, terpene resin, and fat. It is possible to use petroleum resins of group, alicyclic and aromatic, phenolic resins and the like and hydrogenated products thereof. The moisture-permeable olefin-based resin film in the present invention is an opaque resin sheet that is thin in appearance, but has a property of not allowing a liquid to pass therethrough but allowing water vapor or air to pass therethrough. If it is used as a paper diaper, it means a product that prevents stuffiness and does not let urine escape.

A small amount of conventionally known resins and additives may be added. As the resin, ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer, ethylene / acrylic acid copolymer, ethylene / ethyl acrylate copolymer, ethylene / methyl acrylate copolymer, styrene /
Ethylene / butylene / styrene block copolymer, ethylene / propylene copolymer, ethylene / stain copolymer, polybutene, wax and acid, metal salt of acid, or the above polymer or copolymer modified with halogen or the like Alternatively, liquid oil or the like can be used.

Fillers such as clay, talc, calcium carbonate and barium carbonate can also be used as additives, and dilauryl thiodipropionate and pentaerythrityl-wotrakis [3- (3.5-di-t- Butyl-4
-Hydroxyphenyl) propionate], octadecyl-3- (3.5-di-t-stillphenyl) phosphite, 2.6-ditertiary-butyl-4-methylphenol, phenyl-α-naphthylamine and other antioxidants. Can be used.

In the present invention, to compound the adhesive,
You may mix and heat these components in a container, and stir,
Rolls, Banbury mixers, kneaders, extruders and the like which are usually used for mixing polymers can also be used. Since the adhesive composition of the present invention is melted by heating,
It can be formed into various shapes such as a block shape, a pellet shape, a string shape, and a film shape, and used. For application of the adhesive composition of the present invention, a method of melting an adherend by using an ordinary applicator for hot-melt adhesives and adhering adherends to each other, or adhesive to one of the adherends in advance After applying the method, the other adherend is overlaid and pressed,
A method of laminating a film adhesive with a laminator can be used.

The adherend to which the adhesive composition of the present invention can be applied is not limited to any kind, but suitable examples include a moisture-permeable olefin resin film, a porous material such as paper and nonwoven fabric. Examples include base materials. Further, it can also be used for synthetic resins such as polypropylene, polyethylene, polystyrene, polyvinyl chloride, polyester and nylon which are not porous. The content of the tackifier is 80 to 0% by weight, preferably 70 to 20% by weight. Compounding amount is 8
When it exceeds 0% by weight, the characteristics of the base polymer are not exhibited, which is not preferable.

[0016]

EXAMPLES The present invention will be described in detail below with reference to examples. However, the present invention is not limited to the following examples. In the following examples and comparative examples, each physical property was measured by the following methods.

(1) Viscosity (CPS) Measured at 160 ° C. according to JIS K7117

(2) Adhesive Strength An adhesive was applied to a moisture-permeable olefin resin film at 160 ° C. in a bead form (applied amount: 0.1 g / m), and a polypropylene non-woven fabric was immediately pressed to prepare a test piece. This test piece was cut into a strip with a width of 25 mm so that the bead was in the center in the horizontal direction, and the crosshead speed was 300 mm.
180 ° peel strength was measured at room temperature / min.

(3) Heat stability 1 part of hot melt adhesive was placed in a 200 ml tall beaker.
00 g was put and left in an oven at 180 ° C. for 72 hours, and it was observed whether phase separation occurred. ○: No separation ×: Separation

(4) Transparency upon solidification The hot melt adhesive is melted in an oven at 190 ° C,
After taking out and leaving it at room temperature for 24 hours, the transparency was measured by a color difference meter. The L value represents transparency. The measuring method is JI
It carried out based on SZ8722. The reflected light of the opaque adhesive becomes bright because a large amount of light is reflected on the adhesive surface, while the reflected light of the transparent adhesive becomes dark because the light does not reflect on the adhesive surface and is transmitted. Therefore, the brightness L value of the reflected light becomes larger as the adhesive becomes more opaque.

(5) Exudation Property A hot-melt adhesive melted at 160 ° C. was dropped onto a release paper, and a moisture-permeable olefin resin film was stuck to the release paper for 10 minutes. This laminated test piece was put in a hot air dryer at 60 ° C. for 72 hours, and the degree of bleeding to the moisture-permeable olefin resin film was measured. The measurement method was based on JIS Z8722, and the difference dL = Ls-Lo between the brightness (Lo) of the reflected light in the initial state and the brightness (Ls) of the reflected light of the above-mentioned treated sample was measured by a color difference meter. When it exudes into a moisture-permeable olefin resin film,
Since the transparency of the film increases, Ls <Lo, and dL
Is a negative value. In addition, the degree of bleeding out becomes more transparent. Therefore, the larger the negative value, the worse the bleeding. In addition, the seepage to the moisture-permeable olefin resin film was visually determined. The evaluation criteria for bleeding are as follows. ◯: No bleeding at all. Δ: Although bleeding out, the white color of the moisture-permeable olefin resin film can be seen. X: The moisture-permeable olefin resin film oozes out to the extent that the white color cannot be seen.

Example 1 U-Lexene propylene / butene-1 as a non-crystalline polyolefin having a weight ratio of 65/35 is U.
60 wt% of T2780 (amorphous propylene / butene-1 random copolymer) and 40 wt% of hydrogenated terpene resin (Clearon K100, manufactured by Yasuhara Chemical Co., Ltd.) as a tackifier are heated and melt mixed at 180 ° C. to hot melt. An adhesive was prepared. Then, each physical property of the obtained adhesive was measured.

Example 2 Except that the tackifier in Example 1 was changed to hydrogenated DCPD resin (ECR227, manufactured by Tonex).
A hot melt adhesive was obtained in the same manner as in Example 1. Then, each physical property of the obtained adhesive was measured.

Example 3 U-Lexene propylene / butene-1 weight ratio of 65/35 which is an amorphous polyolefin and is a trade name U
Hot melt by mixing 40 wt% of T27200 (amorphous propylene / butene-1 random copolymer) and 60 wt% of hydrogenated terpene resin (Clearon K100, Yasuhara Chemical Co., Ltd.) as a tackifier by heating, melting and mixing at 180 ° C. An adhesive was prepared. Then, each physical property of the obtained adhesive was measured.

Example 4 In Example 3, the tackifier was hydrogenated DCPD resin (E
A hot melt adhesive was obtained in the same manner as in Example 3, except that CR227, manufactured by Tonex Co., Ltd. was used. Then, each physical property of the obtained adhesive was measured.

Example 5 UT manufactured by Ube Lexen as an amorphous polyolefin and having a propylene / ethylene weight ratio of 85/15
60% by weight of 2585 (amorphous propylene / ethylene random copolymer) and 40% by weight of hydrogenated terpene resin (Clearon K100, Yasuhara Chemical Co., Ltd.) as a tackifier are heated and melt mixed at 180 ° C. to form a hot melt adhesive. Was prepared. Then, each physical property of the obtained adhesive was measured.

Comparative Example 1 A hot melt adhesive was obtained in the same manner as in Example 1 except that the tackifier was changed to hydrogenated alicyclic resin (Alcon P100, manufactured by Arakawa Chemical Co., Ltd.). Then, each physical property of the obtained adhesive was measured.

Comparative Example 2 Except that the tackifier in Example 1 was changed to hydrogenated alicyclic resin (IMARB P100, manufactured by Idemitsu Petrochemical).
A hot melt adhesive was obtained in the same manner as in Example 1. Then, each physical property of the obtained adhesive was measured.

Comparative Example 3 A hot melt adhesive was obtained in the same manner as in Example 3, except that the tackifier was changed to hydrogenated alicyclic resin (Alcon P100, manufactured by Arakawa Chemical Co., Ltd.). Then, each physical property of the obtained adhesive was measured.

Comparative Example 4 Except that the tackifier in Example 3 was changed to hydrogenated alicyclic resin (IMARB P100, manufactured by Idemitsu Petrochemical).
A hot melt adhesive was obtained in the same manner as in Example 3. Then, each physical property of the obtained adhesive was measured.

Comparative Example 5 A hot melt adhesive was obtained in the same manner as in Example 5, except that the tackifier was changed to hydrogenated alicyclic resin (Alcon P100, manufactured by Arakawa Chemical Co., Ltd.). Then, each physical property of the obtained adhesive was measured.

Comparative Example 6 A hot melt adhesive was obtained in the same manner as in Example 1 except that the tackifier was changed to an alicyclic resin (ESCOLETS 2101, manufactured by Tonex) in Example 1. Then, each physical property of the obtained adhesive was measured.

[0033]

[Table 1]

As is clear from the results shown in Table 1, the hot melt adhesives of Comparative Examples have a transparency at the time of solidification of less than 40 as measured by a color difference meter and are transparent to the naked eye. The bleeding of this hot melt adhesive to the moisture-permeable olefin resin film has a dL value of less than -8 as measured by a color difference meter, and the bright and dark are distinct and conspicuous, whereas the hot melt adhesive of the example is transparent at the time of solidification. The L value by a color difference meter is 40 or more, and it is opaque by visual observation. As for the bleeding, the dL value by the color difference meter is −8 or more, and the brightness is not clearly defined and is reduced.

[0035]

The hot melt adhesive of the present invention is
The bleeding into the moisture-permeable olefin-based resin film can be reduced, there is no phase separation at the time of melting, and the viscosity is appropriate, so the coating performance is also good.

Claims (3)

[Claims] 1. A number average molecular weight of 1,000 to 20,000.
A hot-melt adhesive comprising 0, an amorphous polyolefin containing 20% by weight or more of a propylene component, and a tackifier, which is transparent in a molten state and opaque at room temperature. 2. The hot melt adhesive according to claim 1, wherein the opacity of the hot melt adhesive at room temperature has an L value of 40 or more, which is a value measured by a color difference meter. 3. The hot melt adhesive according to claim 1, which is for a moisture-permeable olefin resin film.