JP2001294842A - Method for producing pressure-sensitive adhesive resin pellet and method for producing hot-melt pressure- sensitive adhesive pellet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a pressure-sensitive adhesive resin pellet capable of surely preventing occurrence of blocking not only immediately after production but also in the case of long-term preservation. SOLUTION: This method for producing a pressure-sensitive adhesive resin pellet comprises melting a pressure-sensitive adhesive resin 1, leading the molten resin to a thin hole 3a at a fixed velocity to form the pressure-sensitive adhesive resin, then cutting the formed resin in water 4 containing a self-adhesion preventing substance (preferably talc, silica, etc.), bringing cut pieces, namely pellets 6 of the pressure-sensitive adhesion resin into contact with water containing the self-adhesion preventing substance for a fixed time and drying the pellets.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing pellets of a pressure-sensitive adhesive resin and a hot-melt pressure-sensitive adhesive, and more particularly, to a method of producing a pressure-sensitive adhesive resin while preventing blocking (rebinding) caused by contact between the pellets. The present invention relates to a method for producing pellets and hot melt adhesive pellets.

[0002]

2. Description of the Related Art When an adhesive resin is pelletized, it cannot be cut when the adhesive resin is in a molten state. Adhesive resin adheres and it is difficult to smoothly pelletize. Also, once pelletized,
Since the adhesive resin pellets are rebound immediately, it has been very difficult to obtain adhesive resin pellets on an industrial scale.

Further, in the case of a sticky resin pellet having high room temperature adhesiveness, the sticky pellets are gradually rebound by their own weight, and it has been difficult to maintain the pellet state for a long period of time. In order to solve the above-mentioned problems, in the case of the adhesive rubber, the adhesive rubber to be pulverized is cooled using a refrigerant such as liquid nitrogen, and is subjected to low-temperature pulverization or freeze pulverization. That is, the pulverization is performed in a state in which the adhesive rubber is cooled to an extremely low temperature so that the adhesiveness is not developed. However, when this method is carried out industrially, there is a problem that the cost is high because the crushing device and accessory equipment become large and complicated. Moreover, even if the sticky rubber can be pelletized as described above, the sticky rubber pellets re-bond to each other during storage, and it is also difficult to maintain the pellet state for a long time.

On the other hand, in the case of the adhesive rubber, the rubber to be crushed is made to coexist with a liquid such as water or alcohol, and the crushing is performed under conditions in which these liquids evaporate. A method of removing as heat is also known. That is, the pulverization is performed by using the heat of vaporization of the liquid to reduce the adhesiveness of the adhesive rubber. However, similar to the above-described method using a refrigerant such as liquid nitrogen, even if an adhesive rubber pellet can be obtained,
Upon storage, the sticky rubber pellets re-bound together, and it was difficult to maintain the pellet state for a long period of time.

On the other hand, Japanese Patent Application Laid-Open No. 3-181525 discloses a method for pulverizing an olefin rubber.
A method is disclosed in which a heated olefin-based rubber is pulverized by shearing to obtain a powder, which is then cooled while the powder is hot or in a state where the powder is not in contact with each other, and then mixed with a self-adhesion preventing powder. ing. According to this method, the olefin rubber can be easily powdered, and an olefin rubber powder that can be stored for a long time can be obtained.

[0006] However, although olefin-based rubber can provide a certain effect, it cannot cope with various adhesive resins other than olefin-based rubber. Further, pelletization of the hot melt pressure-sensitive adhesive obtained by solution polymerization has been conventionally performed by the following method. That is, in the method, the hot melt adhesive is polymerized in a polymerization kettle, and the solvent is removed by heating in the same polymerization kettle,
Next, the hot melt adhesive is drawn out into a drum and cooled. Thereafter, the hot-melt pressure-sensitive adhesive is melted again by a drum heating / supplying device, introduced into an extruder, and cut by an underwater cutter attached immediately after a die of the extruder to obtain pellets. In the method (2), the hot melt adhesive is polymerized in a polymerization vessel, the adhesive solution is transported to a desolvation facility, the solvent is removed, the solution is extracted into a drum, and cooled. Thereafter, the hot melt pressure-sensitive adhesive is remelted by a drum heating / supplying device, introduced into an extruder, and cut by an underwater cutter attached immediately after a die of the extruder to obtain pellets.

[0007] Therefore, in the method or the method, there is a problem that the hot melt pressure-sensitive adhesive is heated for a long time and the tackiness is deteriorated.

[0008]

SUMMARY OF THE INVENTION It is an object of the present invention to easily pelletize various adhesive resins, and to effectively suppress the occurrence of blocking immediately after pelletization and during long-term storage. An object of the present invention is to provide a method for producing the obtained adhesive resin pellet.

Another object of the present invention is to facilitate the pelletization of a hot-melt pressure-sensitive adhesive, and to effectively prevent the occurrence of blocking immediately after pelletization and when stored for a long period of time. To provide a method for producing hot melt pressure-sensitive adhesive pellets.

[0010]

Means for Solving the Problems The first invention of the present application is a method for producing a sticky resin pellet, comprising the steps of melting the sticky resin, guiding it to pores at a constant speed, and molding the sticky resin. A step of cutting the formed adhesive resin in water containing a substance for preventing self-adhesion, and a step of bringing a cut piece of the adhesive resin into contact with water containing the substance for preventing self-adhesion for a predetermined time; Drying the cut pieces of the adhesive resin.

The second invention is a method for producing hot melt pressure sensitive adhesive pellets, in which a hot melt pressure sensitive adhesive sent out in a molten state from a desolvation equipment is guided into pores at a constant speed to form the hot melt pressure sensitive adhesive. And cutting the molded hot melt adhesive in water containing a substance for preventing self-adhesion, and cutting the cut piece of the hot melt adhesive into water containing the substance for preventing self-adhesion. The method includes a step of contacting for a predetermined time, and a step of drying the cut piece of the hot melt adhesive after being brought into contact with water containing the substance for preventing self-adhesion.

In a specific aspect of the first and second inventions, talc having an average particle diameter of 10 μm or less is used as the substance for preventing self-adhesion. Hereinafter, details of the present invention will be described.

In the following, the description common to the first and second aspects of the invention will be described with reference to the present invention (first and second aspects of the invention).
The description will be made as follows. The adhesive resin used in the first invention is not particularly limited as long as it is soft and adhesive at normal temperature, and examples thereof include polyisobutylene, butyl rubber, ethylene-propylene rubber, ethylene-propylene terpolymer, styrene-isoprene-styrene. Rubber, styrene-ethylene-butadiene-styrene rubber,
Examples include acrylic rubber, acrylate-acrylonitrile copolymer rubber, olefin-based rubber such as chlorosulfonated polyethylene rubber and fluorine rubber, and vulcanized and unvulcanized elastomers.

The hot-melt pressure-sensitive adhesive used in the second invention is a hot-melt pressure-sensitive adhesive which can be applied by a hot-melt method. Is a hot-melt pressure-sensitive adhesive that causes blocking of the pellets in the paper bag placed in the bag, and generally includes a polymer mainly having a glass transition point at 30 ° C. or lower. Specifically, (meth) acrylic copolymer, polyisobutylene, butyl rubber, ethylene-propylene rubber, ethylene-propylene terpolymer, styrene-isoprene-styrene rubber,
Styrene-ethylene-butadiene-styrene rubber, acrylic rubber, acrylate-acrylonitrile copolymer rubber, olefin-based rubber such as chlorosulfonated polyethylene rubber and fluorine rubber, and vulcanized and unvulcanized elastomers. .

That is, the above-mentioned pressure-sensitive adhesive resin and hot-melt pressure-sensitive adhesive which are the object of the present invention usually have a glass transition point of 30 ° C. or lower. Adhesive resins and hot-melt adhesives having a glass transition point higher than 30 ° C. are solidified at room temperature, and therefore have no adhesiveness or fluidity and are less likely to be blocked. Therefore, it is not necessary to add a substance for preventing self-adhesion to the cooling water according to the present invention.

The molecular weight of the adhesive resin or hot melt adhesive used in the present invention is preferably large. JIS K
190 ° C. using a Brookfield type single cylinder rotary viscometer and a double cylinder rotary viscometer according to the viscosity test of 7117.
Has a viscosity of preferably 6,000 mPa · s or more, more preferably 60,000 mPa · s or more. If the viscosity is lower than the above range, creep tends to occur, and the anti-blocking effect is reduced.

In the production method of the first invention, the adhesive resin can be melted by any method, for example, a method of melting by heating in a batch or a method of melting by shearing heat using an extruder. Can be

Further, in the second invention, the hot-melt pressure-sensitive adhesive sent out in a molten state from the desolvation equipment is guided to the pores. That is, in order to prevent the adhesive from deteriorating due to the heating step, the adhesive is brought into a molten state in the desolvation step, and is immediately led to the pores while being controlled to the optimum temperature for cutting.
Therefore, one cooling / reheating step in the conventional method can be omitted, and deterioration of the hot melt adhesive is suppressed.

As the desolvation apparatus, a polymerization vessel may be used as it is, or a so-called thin-layer desolvation apparatus may be used. The molten adhesive resin or hot melt adhesive is guided into the pores at a constant speed, and is extruded from the pores to be formed. In this molding, the melted pressure-sensitive adhesive resin or hot-melt pressure-sensitive adhesive is guided at a constant speed to a die having pores of a desired shape using a pump or an extruder. Depending on the shape of the pores, the adhesive resin or hot melt adhesive is formed into a rod-shaped or plate-shaped strand having a uniform thickness, thickness or width.

The size of the die pores and the discharge speed of the adhesive resin or hot melt adhesive are not particularly limited. However, when considering the appropriate dimensions as a pellet shape, it is desirable to use the pores having an opening area of 0.5 mm ² 25 mm ^2, The length of the molded body ejected from pores is 10mm or less It is desirable.
By shaping into a rod shape or a strand shape having such dimensions, handling in manufacturing a final product using an adhesive resin pellet or a hot-melt adhesive pellet becomes easy.

The speed at which the pressure-sensitive adhesive or hot-melt pressure-sensitive adhesive is discharged from the pores is not particularly limited, but it is necessary to adjust the speed with the balance with the cooling speed.

In the present invention, an adhesive resin or hot melt adhesive formed in water containing the above-mentioned substance for preventing self-adhesion is cut. In this case, since water exerts a cooling effect, it is necessary that the temperature be set lower than that of the molded resin.

In pelletizing, it is desirable that the temperature of the pressure-sensitive adhesive resin or hot-melt pressure-sensitive adhesive is slightly higher than its softening point, that is, about 1 to 10 ° C. higher than the softening point. When the temperature is higher than the softening point by 10 ° C. or more, the adhesive resin or hot melt adhesive adheres to the blade of the pelletizer, and cutting may be difficult. Conversely, when the temperature of the pressure-sensitive adhesive resin or hot-melt pressure-sensitive adhesive is lower than the softening point, it becomes difficult to discharge from the pores.

The cutting of the adhesive resin is preferably performed by using an underwater pelletizer since cooling can be rapidly performed. As a preferable underwater pelletizer, for example, an underwater pelletizer described in US Pat. No. 4,663,099 is used.

When cutting the adhesive resin or hot melt adhesive, a water stream is formed near the cutting blade so that the cut pieces, ie, the pellets, do not come into contact with each other immediately after the cutting, so that the cut pellets move one after another. It is desirable to configure.

The above-mentioned substance for preventing self-adhesion added to the cooling water includes various powders, silicones and surfactants, but does not significantly affect the final product when the final processing of the pellets is performed. For this purpose, inorganic self-adhesion preventing substances such as talc and silica are preferably used. Inorganic self-adhesion preventive substances have little effect on adhesive resins and hot melt adhesives and do not change during final product processing, especially when processing as adhesives, so they have little effect on product design .

Although the size of the inorganic self-adhesion preventing substance and the amount added to the cooling water are not particularly limited, those having an average particle diameter of 10 μm or less are preferably used. If the average particle size exceeds 10 μm, it may be difficult to adhere evenly to the cut adhesive resin or hot melt adhesive pellets, and although the initial anti-blocking property is exhibited, anti-blocking during long-term storage is exhibited. Sex may not be enough. In addition, there is a possibility that the substance for preventing self-adhesion may precipitate at a staying point in the circulation path of the circulating cooling water.

Particularly preferably, talc having an average particle diameter of 10 μm or less is used as the substance for preventing self-adhesion.
The addition amount of the substance for preventing self-adhesion is desirably an amount sufficient to coat the pellets in the production of the pellets. However, it is not desirable to add an excessive amount of anti-self-adhesive substance that interferes with the final processing. Therefore, the amount of the self-adhesion preventing substance added to the cooling water is desirably in the range of 1 to 10% by weight.

More preferably, the self-adhesion preventing substance is desirably attached at a ratio of 0.1 to 2.0% by weight based on the total amount of the adhesive resin pellets or the hot melt adhesive pellets. If the content is less than 0.1% by weight, the expected anti-blocking effect may not be sufficiently exerted in some cases.
If the amount is more than 0% by weight, the quality of the final product, especially the pressure-sensitive adhesive, may be adversely affected.

In the present invention, after the cutting, the pellet is brought into contact with water containing a substance for preventing self-adhesion for a predetermined time. The predetermined time is the time required for the self-adhesion preventing substance to adhere to the pellet, and the type of the adhesive resin or hot melt adhesive used, the dimensions of the pellet, the type of the self-adhesion preventing substance, Since it varies depending on the dimensions and the like, it cannot be uniquely determined, but is usually about 1 second to 10 minutes. When the contact time is shorter than 1 second, it is difficult to sufficiently adhere the self-adhesion preventing substance to the surface of the adhesive resin or hot melt adhesive. Although the substance adheres sufficiently, the processing time becomes longer.

In the present invention, after the substance for preventing self-adhesion is attached to the pellets as described above, the pellets are dried. That is, a drying step is performed to remove the cooling water. For this drying, an appropriate method such as natural drying or drying with cold air can be used.

[0032]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a method for producing an adhesive resin pellet according to the present invention will be described with reference to FIG.

In FIG. 1, an adhesive resin 1 is supplied to a hopper 2 a of a melt extruder 2. The adhesive resin supplied to the hopper 2a is melted by the melt extruder 2 and guided to a die 3 having pores 3a. The adhesive resin guided to the pores 3a is formed into a strand shape or a plate shape. The exit side of the pores 3 a of the die 3 is exposed to the self-adhesion preventing substance-containing cooling water 4. That is, the formed adhesive resin is extruded from the pores 3 a into the self-adhesion preventing substance-containing cooling water 4, and the extruded molded body is cut by the cutting device 5 to form pellets 6. The pellet 6 is cooled in the self-adhesion-preventing substance-containing cooling water 4 and the self-adhesion-preventing substance adheres to the outer surface thereof.

In the present embodiment, the pellets 6 move downward in the cooling water 4 containing the substance for preventing self-adhesion by gravity, and the pellets come into contact with the substance for preventing self-adhesion for a sufficient time during the movement time. Is done. Therefore, the substance for preventing self-adhesion is securely attached to the outer surface of the pellet.

Next, the pellets 6 are taken out from below the tank 7 in which the self-adhesion-preventing substance-containing cooling water 4 is stored, conveyed by the conveyor 8, and dried during the conveyance. Further, the pellets are dried by passing through the dryer 9 and taken out into the container 10. In the pellets accumulated in the container 10, since the substance for preventing self-adhesion is attached to the outer surface, blocking between the pellets hardly occurs. Further, even when stored for a long time, blocking between the pellets is reliably prevented.

Next, the present invention will be described in more detail by giving specific examples and comparative examples of the present invention. Note that the present invention is not limited to the following embodiments. (Example 1) In a viscosity test of JIS K7117,
Spindle rotation speed 0.5 / min and spindle number SA7
Acrylate that did not rotate when measured in-
Acrylonitrile copolymer rubber (viscosity 8 at 190 ° C.
(At least 000 mPa · s) using an extruder and melt-discharged, and pellets were produced by an underwater cut pelletizing system (manufactured by GALA, product number: TWS-40) schematically shown in FIG. In the cooling water, 3.0% by weight of talc 1 (manufactured by Nippon Mistron Co., Ltd., trade name: Mistron Paper, average particle size: 2.6 μm) was added to 100% by weight of water.

(Example 2) The addition ratio of talc 1 was set to 3.
Except for changing from 0% by weight to 6.0% by weight,
Pellets were produced in the same manner as in Example 1.

Example 3 Talc 2 (manufactured by Nippon Talc, average particle size 1) was used in place of talc 1 as a substance for preventing self-adhesion.
A pellet was produced in the same manner as in Example 1 except that 0.0 μm) was used.

(Example 4)
Except for changing from 0% by weight to 6.0% by weight,
Pellets were produced in the same manner as in Example 3.

Example 5 Pellets were produced in the same manner as in Example 1 except that talc 3 (manufactured by Nippon Talc, average particle size 20.0 μm) was used as a substance for preventing self-adhesion. .

(Example 6)
Except for changing from 0% by weight to 6.0% by weight,
Pellets were produced in the same manner as in Example 5.

(Example 7) As a substance for preventing self-adhesion, silica (trade name: Siebelite M6000, manufactured by Shibelco Co., Ltd.)
A pellet was produced in the same manner as in Example 1 except that an average particle diameter of 3.0 μm was used.

Example 8 The addition ratio of silica was 3.0.
Pellets were produced in the same manner as in Example 7, except that the weight% was changed to 6.0% by weight.

(Example 9) In a viscosity test according to JIS K7117, an acrylate ester having a viscosity of 10,000 mPa · s at 190 ° C measured using a spindle rotation speed of 1.0 / min and a spindle number of SA6 was used.
The acrylonitrile copolymer rubber was melt-discharged using an extruder, and pellets were produced in the same manner as in Example 1 below.

Example 10 The addition ratio of talc 1 was
Pellets were produced in the same manner as in Example 9, except that the weight was changed from 3.0% by weight to 6.0% by weight.

Example 11 Pellets were produced in the same manner as in Example 9 except that talc 2 (manufactured by Nippon Talc, average particle size 10.0 μm) was used as a substance for preventing self-adhesion.

(Example 12)
Pellets were produced in the same manner as in Example 11, except that the weight was changed from 3.0% by weight to 6.0% by weight.

Example 13 Pellets were produced in the same manner as in Example 9 except that talc 3 (manufactured by Nippon Talc, average particle size 20.0 μm) was used as a substance for preventing self-adhesion.

(Example 14)
Pellets were produced in the same manner as in Example 13, except that the weight was changed from 3.0% by weight to 6.0% by weight.

(Example 15) As a substance for preventing self-adhesion, silica (trade name: Siebelite M600, manufactured by Shibelco Co., Ltd.)
0, average particle size of 3.0 μm)
Pellets were produced in the same manner as in Example 9.

(Example 16) The addition ratio of silica was 3.
Except for changing from 0% by weight to 6.0% by weight,
Pellets were produced in the same manner as in Example 15.

(Example 17) In a viscosity test according to JIS K7117, butyl acrylate having a viscosity of 190,000 mPa · s at 190 ° C. after desolvation measured with a spindle rotation speed of 0.5 / min and a spindle number of SA7. -The ethyl acetate solution of the methyl methacrylate block copolymer was led to a desolvation device, and the melt after desolvation was led to a single screw extruder through a pipe. This single screw extruder melts and discharges,
Using an underwater cut pelletizing system, pellets were produced in the same manner as in Example 1 below.

(Example 18)
A pellet was produced in the same manner as in Example 17, except that the weight was changed from 3.0% by weight to 6.0% by weight.

Example 19 The same procedure as in Example 17 was carried out except that talc 2 (manufactured by Nippon Talc, average particle size 10.0 μm) was used instead of talc 1 as a substance for preventing self-adhesion. To produce pellets.

(Example 20) The addition ratio of talc 2 was
A pellet was produced in the same manner as in Example 19, except that the weight was changed from 3.0% by weight to 6.0% by weight.

Example 21 Pellets were produced in the same manner as in Example 17 except that talc 3 (manufactured by Nippon Talc, average particle diameter 20.0 μm) was used as a substance for preventing self-adhesion. .

(Example 22) The proportion of talc 3 added was
A pellet was produced in the same manner as in Example 21, except that the weight was changed from 3.0% by weight to 6.0% by weight.

(Example 23) As a substance for preventing self-adhesion, silica (trade name: Siebelite M600, manufactured by Shibelco Co., Ltd.)
0, average particle size of 3.0 μm)
Pellets were produced in the same manner as in Example 17.

(Example 24)
Except for changing from 0% by weight to 6.0% by weight,
Pellets were produced in the same manner as in Example 23.

(Example 25) In a viscosity test according to JIS K7117, butyl acrylate having a viscosity of 190 mPa · s at 190 ° C. after desolvation measured by spindle number 1.0 / min and spindle number SA6 in a viscosity test according to JIS K7117. −
The ethyl acetate solution of the methyl methacrylate block copolymer was led to a desolvation apparatus, and pellets were produced in the same manner as in Example 1.

(Example 26)
A pellet was produced in the same manner as in Example 25, except that the weight was changed from 3.0% by weight to 6.0% by weight.

Example 27 Pellets were produced in the same manner as in Example 25, except that talc 2 (manufactured by Nippon Talc, average particle size 10.0 μm) was used as a substance for preventing self-adhesion.

(Example 28) The addition ratio of talc 2 was
A pellet was produced in the same manner as in Example 27, except that the weight was changed from 3.0% by weight to 6.0% by weight.

Example 29 Pellets were produced in the same manner as in Example 25 except that talc 3 (manufactured by Nippon Talc, average particle size 20.0 μm) was used as a substance for preventing self-adhesion.

Example 30 The proportion of talc 3 added was
A pellet was produced in the same manner as in Example 29, except that the weight was changed from 3.0% by weight to 6.0% by weight.

(Example 31) As a substance for preventing self-adhesion, silica (manufactured by Shibelco, trade name: Seebelite M600)
0, average particle size of 3.0 μm)
Pellets were produced in the same manner as in Example 25.

(Example 32) The addition ratio of silica was 3.
Except for changing from 0% by weight to 6.0% by weight,
Pellets were produced in the same manner as in Example 31.

Comparative Example 1 A pellet was produced in the same manner as in Example 1 except that talc 1 as a substance for preventing self-adhesion was not added.

(Comparative Example 2) In the underwater cut pelletizing system used in Example 1, cooling water was extracted, and the adhesive resin was cut in the air. .

Comparative Example 3 Pellets were produced in the same manner as in Example 9 except that talc 1 as a substance for preventing self-adhesion was not added.

(Comparative Example 4) In the underwater cut pelletizing system used in Example 9, the cooling water was extracted, and the adhesive resin was cut in the air. .

Comparative Example 5 A pellet was produced in the same manner as in Example 17 except that talc 1 as a substance for preventing self-adhesion was not added.

(Comparative Example 6) In the underwater cut pelletizing system used in Example 17, cooling water was drained.
Pellets were produced in the same manner as in Example 17 except that the adhesive resin was cut in the air.

(Comparative Example 7) After the solvent removing step in Example 17, the molten resin was once taken out into a drum, cooled, melted with a drum melter DG201S (manufactured by Nordson), and supplied to a single screw extruder. Pellets were produced in the same manner as in Example 17.

Comparative Example 8 Pellets were produced in the same manner as in Example 25 except that talc 1 as a substance for preventing self-adhesion was not added.

(Comparative Example 9) In the underwater cut pelletizing system used in Example 25, cooling water was drained.
Pellets were produced in the same manner as in Example 25 except that the adhesive resin was cut in air.

(Comparative Example 10) After the solvent removing step in Example 25, the molten resin was once taken out into a drum and cooled, and then a drum melter DG201S (manufactured by Nordson) was used.
And fed to a single screw extruder to produce pellets in the same manner as in Example 25.

(Evaluation of Examples and Comparative Examples) 25 kg of pellets immediately after production were put into a paper bag and packed to prepare a pellet bag. Thereafter, the degree of blocking after standing at room temperature for 1 hour was evaluated in the following manner, and the result was defined as "initial blocking property". In addition, the degree of blocking after allowing the pellet bag to stand at 40 ° C. for 7 days was evaluated in the following manner,
This was referred to as “time-blocking property”.

Evaluation of blocking property: Pellets taken out of the pellet bag, in which lump due to blocking occurred at 20% or more of the total weight, were evaluated as “X”, and less than 20% were evaluated as “O”. In the case of 0%, it was determined to be “◎”.

The results are shown in Tables 1 to 4 below.

[0081]

[Table 1]

[0082]

[Table 2]

[0083]

[Table 3]

[0084]

[Table 4]

[0085]

According to the method for producing a sticky resin pellet according to the first aspect of the present invention, the sticky resin is melted, guided into pores at a constant speed, molded, and then cut in water containing a substance for preventing self-adhesion. . Thereafter, the cut piece of the adhesive resin is brought into contact with water containing the substance for preventing self-adhesion for a predetermined time, so that the substance for preventing self-adhesion adheres to the cut piece, that is, the outer surface of the pellet. Therefore, by drying the above-mentioned pellets, it becomes possible to provide an adhesive resin pellet which hardly causes blocking even immediately after production and after storage for a long period of time.

In the first invention, when talc having an average particle size of 10 μm or less is used as the substance for preventing self-adhesion, the adhesive resin is hardly affected and the adhesive resin is denatured. Without this, talc can be evenly adhered to the adhesive resin pellets, so that not only the initial anti-blocking property but also the long-term anti-blocking property can be reliably exhibited. In addition, when the water containing the substance for preventing self-adhesion is circulated, the problem that the substance for preventing self-adhesion precipitates at the staying point in the circulation path hardly occurs.

According to the method for producing hot-melt pressure-sensitive adhesive pellets according to the second invention, the hot-melt pressure-sensitive adhesive sent out in a molten state from the desolvation equipment is guided into the pores at a constant speed and molded. Thereafter, the hot melt adhesive is cut in water containing the substance for preventing self-adhesion, and the cut pieces or pellets of the hot melt adhesive are brought into contact with water containing the substance for preventing self-adhesion for a predetermined time. Therefore, as in the case of the first invention, the self-adhesion preventing substance is securely and uniformly attached to the outer surface of the pellet. Therefore, after drying the pellet, not only excellent initial blocking performance,
It becomes possible to provide a hot-melt pressure-sensitive adhesive pellet which does not easily cause blocking even when stored for a long time.

Further, since the hot-melt pressure-sensitive adhesive pellets are immediately produced by using the hot-melt pressure-sensitive adhesive sent out in a molten state from the desolvation equipment, a long heating step as in the conventional method is not required. Therefore, not only can the process be simplified, but also the deterioration of the hot melt adhesive can be suppressed.

In the second invention, when talc having an average particle size of 10 μm or less is used as the substance for preventing self-adhesion, it hardly affects the adhesive resin.
And without causing the denaturation of the adhesive resin, talc can be evenly attached to the adhesive resin pellets,
Therefore, not only the initial anti-blocking property but also the anti-blocking performance over a long period of time can be reliably developed. In addition, when the water containing the substance for preventing self-adhesion is circulated, the problem that the substance for preventing self-adhesion precipitates at the staying point in the circulation path hardly occurs.

As described above, according to the method for producing pressure-sensitive adhesive resin pellets and hot-melt pressure-sensitive adhesive pellets of the present invention, blocking immediately after pellet production and during long-term storage can be reliably suppressed. The adhesive resin pellets and the hot melt adhesive can be easily stored until shipment, and stable adhesive resin pellets or hot melt adhesive pellets can be provided.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of an apparatus used for a method for producing an adhesive resin pellet according to an embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Adhesive resin 2 ... Melt extruder 3 ... Die 3a ... Pores 4 ... Cooling water containing a substance for preventing self-adhesion 5 ... Cutting device 6 ... Pellets 7 ... Tank 8 ... Conveyor 9 ... Dryer 10 ... Container

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C08L 23:00 C08L 23:00 F term (Reference) 4F071 AA01 AB26 AE11 AF58 AG12 AG26 AG28 AG32 AH19 BB06 BC07 4J040 DA021 DA121 DA141 DA191 DC091 DF041 DF051 DF081 DM011 HA306 HA356 JA08 JB01 JB09 KA03 KA09 LA01 LA02 LA11 QA04 QA09

Claims (4)

[Claims] 1. A step of melting an adhesive resin, guiding the adhesive resin into pores at a constant speed and molding the adhesive resin, and cutting the molded adhesive resin in water containing a substance for preventing self-adhesion. A step of contacting the cut piece of the adhesive resin with water containing a substance for preventing self-adhesion for a predetermined time, and a step of drying the cut piece of the adhesive resin. Method for producing resin pellets. 2. The method according to claim 1, wherein the substance for preventing self-adhesion is talc, and the average particle diameter of the talc is 10 μm or less. 3. A step of introducing a hot melt adhesive fed in a molten state from a desolvation equipment into pores at a constant speed to form the hot melt adhesive, and self-adhering the formed hot melt adhesive. Cutting in water containing an anti-adhesion substance; contacting the cut piece of the hot melt adhesive with water containing the self-adhesion prevention substance for a predetermined time; Drying the cut pieces of the hot-melt pressure-sensitive adhesive after contact with the contained water. 4. The method according to claim 3, wherein the self-adhesion preventing substance is talc, and the average particle diameter of the talc is 10 μm or less.