JPH08209089A - Production of hot-melt adhesive - Google Patents

Abstract

PURPOSE: To obtain a hot-melt adhesive suitable for bonding a water vapor permeable olefinic film, long in open time and excellent in coating workability by heating and melting a part of a tackifier resin, blending the resin with a homopolymer of butene-1 in a molten state and then adding an antioxidant. CONSTITUTION: This adhesive is obtained by heating and melting (A) a part or the whole of preferably 40-300 pts.wt. tackifier resin such as an aliphatic petroleum resin [based on 100 pts.wt. of (co)polymer of butene-1], heating, melting and blending the resin with (B) a homopolymer of butene-1 or its copolymer, and then, heating, melting and blending the blend with (C) preferably 0.1-5 antioxidant such as 2,4-bis(n-octylneo)-6-(4-hydroxy-3,5-di-t-butylanilino)-1,3,5- triazine and the rest of the tackifier resin. The number-average molecular weight of the component B is preferably 20,000-100,000.

Description

Detailed Description of the Invention

[0001]

The present invention uses a homopolymer of butene-1 having a long open time and a low melt viscosity or a copolymer thereof as a base polymer, and is particularly suitable for adhesion of a moisture-permeable olefin resin film. The present invention relates to a method for producing a hot melt adhesive used.

[0002]

2. Description of the Related Art As an adhesive used to bond a breathable olefin resin film used in disposable diapers, sanitary napkins, bed pad components, etc. to other components such as nonwoven fabric and paper , For example, number average molecular weight 500 to 20,000, ethylene content 10 to 8
A hot melt adhesive containing a base polymer composed of 0% by weight of an amorphous ethylene-propylene random copolymer and a wax or a tackifying resin has been proposed (see JP-A-5-148465).

In the above hot melt adhesive, when waxes are mixed, the solidification rate after coating is fast (open time is short), so that it is difficult to bite into nonwoven fabric or paper and the adhesive strength is weak. In addition, when the tackifying resin is blended, there is a drawback that the effect of preventing seepage from the fine pores of the moisture-permeable olefin resin film is not sufficient.

As a hot melt adhesive which has a long open time and is preferably used for bonding non-woven products, butene-
A hot melt adhesive containing the homopolymer of No. 1 or a copolymer thereof as a base polymer has been proposed (JP-A-2-1).
See 96878).

[0005]

Butene-1 is disclosed in the above publication.
-Duraflex 8910 (current trade name is polybutylene DP-89) exemplified as ethylene copolymer
When 10) is used, the melt viscosity becomes too high and the coating operation becomes difficult. If the compounding amount of the tackifying resin is increased in order to reduce the melt viscosity, the solidification after coating becomes too fast and the non-woven fabric or paper bites. Is bad, the adhesive strength is weak,
There is exudation from the fine pores of the moisture-permeable olefin resin film.

Further, the above publication describes a method in which a (co) polymer of a base polymer is first melted by heating, and then the remaining components are mixed, but in this method, a high molecular weight (high viscosity) Since the (co) polymer is agitated, the load on the agitator becomes large in a large-sized production apparatus, a large-capacity agitator is required, and the equipment cost increases.

The present invention has been made in view of the above points, and uses as a base polymer a homopolymer of butene-1 having a long open time and a low melt viscosity or a copolymer thereof, and particularly a moisture-permeable olefin-based polymer. It is an object of the present invention to provide a method for producing a hot melt adhesive which is preferably used for adhering a resin film.

[0008]

The method for producing a hot melt adhesive of the present invention comprises a butene-1 homopolymer or / and its copolymer, a tackifying resin and an antioxidant as main components. In producing a hot-melt adhesive, a part or (and) all of the tackifying resin is heated and melted, and a homopolymer of butene-1 or a copolymer thereof is added thereto and heated and melted and mixed. The remaining amount of the antioxidant and the tackifying resin is added and the mixture is heated, melted and mixed, thereby achieving the above object.

In the present invention, a homopolymer of butene-1 and / or a copolymer thereof is used as a base polymer, and as a copolymer of butene-1, butene-1 and other α- Examples thereof include copolymers with olefins (ethylene, propylene, etc.). When the content of butene-1 is small, solidification becomes fast and the open time becomes short when the adhesive composition is cooled, so that it is preferably 50 mol% or more, more preferably 70 mol% or more. Butene-
The homopolymer of 1 and its copolymer may be used alone or in combination of two or more kinds.

The butene-1 homopolymer or copolymer thereof has a number average molecular weight of preferably 10,000 to 500,000, more preferably 20,000 to 10.
It is 10,000. When it is less than 10,000, not only the cohesive force of the obtained adhesive decreases and desired adhesive strength cannot be obtained, but also the polymer itself becomes sticky, and when molded into pellets, the pellets adhere to each other. In order to prevent this, it is necessary to attach an anti-adhesion agent such as wax to the pellets, which may shorten the open time, which is not preferable, and when it exceeds 500,000. This is because the melt viscosity becomes too high.

Examples of the tackifying resin include aliphatic petroleum resins and hydrogenated products thereof, aromatic petroleum resins and hydrogenated products thereof, alicyclic petroleum resins and hydrogenated products thereof, aliphatic / aromatic petroleum resins and hydrogenated products thereof. Additives, aliphatic / alicyclic petroleum resins and hydrogenated products thereof, terpene resins and hydrogenated products thereof, aromatic modified terpene resins and hydrogenated products thereof, rosin, disproportionated rosin, rosin ester, hydrogenated rosin ester , Disproportionated rosin ester and the like.

Among them, hydrogenated petroleum resins such as aliphatic hydrogenated petroleum resin, alicyclic hydrogenated petroleum resin, aliphatic / aromatic hydrogenated petroleum resin, and aliphatic / alicyclic hydrogenated petroleum resin are preferable. Used. Since the non-hydrogenated tackifying resin may be colored when heated, it is preferably used in the presence of an antioxidant. Further, these tackifying resins may be used alone or in combination of two or more kinds.

The softening temperature of the tackifying resin is JIS
Those having a temperature in the range of 60 to 155 ° C. as measured by the ring and ball softening point measuring method specified in K-2207 are preferably used. This is because if the softening point is lower than 60 ° C, the cohesive force of the adhesive is lowered to make it difficult to obtain a desired adhesive force, and if it exceeds 155 ° C, the viscosity at the time of melting becomes high and the coating operation becomes difficult. However,
The tackifying resin having a softening temperature of lower than 60 ° C. or higher than 155 ° C. may be used in combination with the tackifying resin having a softening temperature of 60 to 155 ° C. as long as it does not impair the object of the present invention.

The amount of the tackifying resin compounded is such that the base polymer butene-1 is a homopolymer or / and a copolymer 1 thereof.
The amount is preferably 40 to 300 parts by weight with respect to 00 parts by weight. This is because if it is less than 40 parts by weight, the melt viscosity becomes high and the coating operation becomes difficult, and if it exceeds 300 parts by weight, solidification after coating becomes fast and the desired open time cannot be obtained.

As the antioxidant, 2,4-bis (n-
Octyl neo) -6- (4-hydroxy-3,5-di-
t-Butylanilino) -1,3,5-triazine, pentaerythrityl-tetrakis [3- (3,5-di-t-
Butyl-hydroxyphenyl) propionate], octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate and the like are preferably used. Tris (2,4
Phosphorus antioxidants such as -di-t-butylphenyl) phosphite are also effective.

The blending amount of the antioxidant is preferably 0.1 to 5 parts by weight with respect to 100 parts by weight of the base polymer and the tackifying resin. If the amount is less than 0.1 parts by weight, the effect of the antioxidant cannot be sufficiently obtained, and the low molecular weight of the butene-1 homopolymer or (and) its copolymer is also obtained by the heat when the adhesive is heated and melted. This is because the progress of chemical reaction leads to a decrease in the melting temperature, and if it exceeds 5 parts by weight, it will be compounded in an amount more than necessary and it is not economical.

In the present invention, oils, waxes, ultraviolet absorbers, fillers and the like may be added, if necessary.

Examples of the oils include paraffin-based, naphthene-based and aroma-based process oils, aromatic oils, and liquid paraffin such as polybutene.

Examples of waxes include polyethylene wax, acid-modified polypropylene wax, paraffin wax and microcrystalline wax.
Since the addition of waxes shortens the open time, it is desirable to use the wax as little as possible.

As the ultraviolet absorber, 2- (5-methyl-hydroxyphenyl) benzotriazole, dimethyl-1- (2-hydroxyethyl) -4-hydroxy-2,2,6,6-tetramethylpiperidine succinate is used. Examples thereof include polycondensates. The addition amount is not particularly limited, but with respect to 100 parts by weight of the base polymer and the tackifying resin,
0.01 to 2 parts by weight is preferable. If the amount is less than 0.01 parts by weight, the effect is not sufficient, and if the amount exceeds 2 parts by weight, the amount is more than necessary and the amount is not economical. Also,
Examples of the filler include talc, clay, calcium carbonate and the like.

[0021]

According to the method for producing a hot melt adhesive of the present invention, a homopolymer of butene-1 or (and) at the time of melting by heating.
Since the copolymer has a low molecular weight, a hot melt adhesive having a low melt viscosity can be obtained without impairing the length of open time. Further, the antioxidant added after the homopolymer of butene-1 or its copolymer has been reduced in molecular weight suppresses the reduction in molecular weight, and prevents the melt viscosity from unnecessarily decreasing. Further, a part or all of the tackifying resin is melted in advance by heating, and the homopolymer of butene-1 or (and) its copolymer is added to the melt, and the mixture is melted by heating. The viscosity does not become too high, and the load on the device does not become high.

[0022]

Next, an embodiment of the present invention will be described. In the following, "parts" means "parts by weight".

Example 1 Alicyclic hydrogenated petroleum resin (softening point 100 ° C., “Alcon P-100”, manufactured by Arakawa Chemical Co., Ltd.) 50
Parts were put into a sigma blade mixer preheated to 180 ° C. and heated to completely melt the resin, and then ethylene-butene-1 copolymer (ethylene content of about 5%, number average molecular weight of about 70) was added thereto. 1,000 "Polybutylene DP-891
0 "made by Shell Chemical Co., Ltd.) 100 parts and added at 180 ° C for 5
The mixture was melted by heating for 0 minutes. Thereafter, 1.0 part of a hindered amine-based antioxidant (“Irganox 1010” manufactured by Ciba-Guy) and the remaining 50 parts of the above alicyclic hydrogenated petroleum resin were added, and the mixture was heated and mixed for about 20 minutes until the whole became uniform. A hot melt adhesive was obtained.

(Example 2) A hot melt adhesive was obtained in the same manner as in Example 1 except that the heat-melt mixing time after adding the ethylene-butene-1 copolymer was 120 minutes.

Example 3 A hot melt adhesive was obtained in the same manner as in Example 1 except that the balance of the alicyclic hydrogenated petroleum resin was 150 parts.

Comparative Example 1 A hot melt adhesive was obtained in the same manner as in Example 1 except that the addition of the hindered amine antioxidant was carried out during the preheating of the alicyclic hydrogenated petroleum resin.

Comparative Example 2 Instead of the ethylene-butene-1 copolymer, an ethylene-propylene copolymer (ethylene content: about 15%, number average molecular weight: about 7,000 "Ubetack 2585" manufactured by Ube Lexen) A hot melt adhesive was obtained in the same manner as Comparative Example 1 except that was used.

Comparative Example 3 A ethylene / propylene copolymer (ethylene content: about 15%, number average molecular weight: about 7,000 "Ubetack 2585" manufactured by Ube Lexen Co., Ltd.) was prepared except that no antioxidant was added. A hot melt adhesive was obtained in the same manner as in Example 1 except that (1) was used.

For each hot melt adhesive obtained,
Melt viscosity, adhesive strength, fracture state, bleeding and thermal stability were measured. These measuring methods and evaluations are as follows.

Melt viscosity According to JIS K-6862, the viscosity at 160 ° C was measured using a BM type viscometer.

Adhesive Strength Hot melt adhesive is applied at 160 ° C., coating amount is about 0.07 g /
The test piece was obtained by coating the moisture-permeable polyethylene film in a beat shape at m, and pressing the polypropylene fiber nonwoven fabric 10 seconds after the coating. This test piece was cut into a strip shape with a width of 15 mm so that the bead was located in the center in the direction parallel to the bead, and the T-shaped peel strength was measured at a peeling speed of 300 mm / min to obtain the adhesive strength.

Destruction State The destruction state of the test piece after the measurement of the adhesive strength was visually determined.

The same test piece as in the case of measuring the exudation adhesive strength was put in a hot air dryer at 60 ° C. for 24 hours and allowed to stand at 20 ° C. for 10 minutes, and then the shape of the bead of the adhesive was measured from the moisture permeable polyethylene film side. The appearance was evaluated by visually judging whether it looks like. Those with no beat shape were marked with ⊚, those that could hardly be distinguished were marked with ◯, and those that could be distinguished were marked with x.

[0034] To see the thermostable thermostable, put a hot-melt adhesive 100g glass bottle, placed in a hot air dryer remains 180 ° C. uncovered, the melt viscosity was measured at 160 ° C. after 72 hours. The results are shown in Table 1.

[0035]

[Table 1]

As is clear from the above results, all of the hot melt adhesives obtained in the respective examples gave good results with respect to adhesive strength and bleeding, and also had low melt viscosity and excellent coating workability. It was In addition, there was little change in melt viscosity due to heating for a long time, and thermal stability was excellent.
On the other hand, the hot melt adhesive according to Comparative Example 1 has a high melt viscosity and is inferior in coating workability, and the hot melt adhesive according to Comparative Example 2 is inferior in adhesiveness to a nonwoven fabric and inferior in exudation. It was The hot melt adhesive according to Comparative Example 3 was inferior in thermal stability.

[0037]

EFFECTS OF THE INVENTION According to the method for producing a hot melt adhesive of the present invention, the open time is long, there is no exudation from the moisture-permeable olefin resin film, and there is little change in the melt viscosity even when heated for a long time. A hot melt adhesive having a low melt viscosity and excellent coating workability can be obtained. In addition, the melt viscosity of the heat-melted mixture at the time of production does not become too high, the load on the apparatus is reduced, and the production with a large-sized production apparatus becomes easy.

Claims (1)

[Claims] 1. When producing a hot-melt adhesive containing butene-1 homopolymer or / and its copolymer, tackifying resin and antioxidant as main components, part of the tackifying resin or ( And) All of them are heated and melted, butene-1 homopolymer or copolymer thereof is added to the mixture, and the mixture is heated and melted. Then, the remaining amount of the antioxidant and the tackifying resin is added, and the mixture is heated and melted and mixed. A method for producing a hot melt adhesive characterized by the above.