JPS62223285A - Hot-melt adhesive - Google Patents

Abstract

PURPOSE:To provide the titled adhesive which is suitable for sue in bonding fibers, gives bond areas having excellent hand and has excellent resistance to water and dry cleaning, consisting mainly of a linear polyurethane polymer obtd. by reacting a high-molecular diol with a diisocyanate and a bifunctional chain extender. CONSTITUTION:A high-molecular diol (A) having an (average) MW of 500-3,000, composed of 60-100wt% polyoxytetramethylenediol and 40-0wt% other high- molecular diol is reacted with a diisocyanate compd. (B) such as diphenylmethane diisocyanate and a bifunctional chain extender (C) such as a 4-10C (aliph. hydrocarbon) diol (e.g., 1,4-butanediol) in a weight ratio of (B+C) to (A+B+C) of 0.15-0.5 and a ratio of 93-99.8 isocyanate groups in the component B to 100 of the sum of the functional groups in the components A and C in the presence of optionally, a catalyst, a stabilizer, etc., e.g., by a pseudo-prepolymer process. The titled adhesive contains at least 60wt% resulting linear polyurethane polymer having an MW of 25,000-80,000.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention provides a method for use in textiles, in particular, which has an excellent texture and improved water resistance and solvent resistance (dry cleaning resistance). It relates to polyurethane-based hot melt adhesives.

[Prior Art] Hot melt adhesives are solvent-free, and bonding is completed instantaneously by heating, providing strong adhesive strength. Therefore, in recent years, many hot melt adhesives for tags have already been developed and commercialized in the adhesive industry for reasons such as streamlining, labor saving, and speeding up the bonding process.

However, currently commercially available hot melt adhesives cannot be used as #a maintenance adhesives for adhesive sewing, adhesive interlining, non-woven fabric binders, patches, names, marks, etc.
It is not always possible to satisfy the texture, water resistance, and solvent resistance of the adhesive part. Commercially available hot melt adhesives include:
Polyolefin, polyamide, polyethylene-vinyl acetate (EVA), polyester, polyurethane, etc. are known, but for example, polyamide-based adhesives, which have relatively high adhesive strength and excellent solvent resistance, are particularly effective for bonding in film form. If this is done, the bonded area will have a rough and hard feel, making it impossible to obtain a bonded area with a good texture that does not impair the characteristics of the outer fabric, and the water resistance when washed with hot water is also unsatisfactory. In addition, polyester adhesives that have a particularly high affinity with polyester woven fabrics have the advantage of high adhesive strength, but have poor solvent resistance. On the other hand, polyurethane adhesives are relatively well-balanced in terms of the texture of the bonded area, water resistance, and solvent resistance to petroleum solvents, but no adhesive has been found that satisfies all the requirements at the same time. In other words, when a film-like polyurethane adhesive is used, one with a good texture at the adhesive part does not have sufficient water resistance and/or solvent resistance, and on the other hand, one with good texture in the adhesive part does not have sufficient water resistance and/or solvent resistance. However, the texture of the bonded area is not satisfactory.

[Problems to be Solved by the Invention] The present invention has been intensively studied to produce a polyurethane-based hot melt adhesive that overcomes the conventional drawbacks, and has thus arrived at the present invention. That is, an object of the present invention is to provide a polyurethane-based hot melt adhesive that has an excellent texture at the bonded portion and has excellent water washing resistance and dry cleaning resistance.

[Means for Solving the Problems] The present invention has been made to solve the above-mentioned problems, and the gist of the invention is as follows.

That is, the main raw materials are a high molecular weight diol (a) having a molecular weight of about 500 to 3000, which is mainly composed of polyoxytetramethylene diol, a divalent isocyanate compound (b), and a bifunctional chain extender (c), b+c)
/(a+b+c) weight ratio of about 0.15 to 0.5, and the main component is a substantially linear polyurethane polymer having a molecular weight of about 25,000 to 80,000. It is something to do.

Hot melt adhesives, especially when used for textiles such as fabrics, must have an appropriate melt viscosity because the resin flows out below the heat-resistant temperature of the outer fabric, penetrates the fabric appropriately, and develops adhesive strength. is necessary. For this purpose, the molecular weight of the polyurethane polymer used in hot melt adhesives must be adjusted within a certain range (i.e., approximately 25,000 to 80,000 in the present invention), and In comparison, it is necessary to keep the molecular weight low. Methods for controlling the molecular weight of polyurethane using the NCo index and using a molecular weight controlling agent are well known.

The NCo index refers to the ratio of the number of isocyanate groups to the total number of functional groups that react with isocyanate groups (100). For example, an NCo index of 100 means that the two are equivalent. There are two ways to adjust the NCo index and lower the molecular weight of polyurethane polymers: raise the NCo index from 100 to 105 to E, or lower it below. Lowering the molecular weight by indexing is not preferred because the molecular weight increases over time due to the reactivity of the remaining isocyanate groups.

The NCo index suitable for wood purposes is about 84-98, more preferably about 93-99.8°. If the NCo index is even smaller than about 83, water resistance, Mm agent properties, mechanical properties, etc. will be poor when used as a hot melt adhesive. Moreover, the melt viscosity when melted becomes too low. On the other hand, when the NGO index exceeds about 100, the adhesive has a high molecular weight, which deteriorates its fluidity when hot, and in the case of fabrics such as nylon, it is difficult to bond unless the temperature is raised above the heat resistance temperature of the fabric. .

Furthermore, when used for adhesive sewing, etc., the problem of warping of the outer fabric due to heat shrinkage occurs, which is not preferable. In the present invention, it is preferable to adjust the NCO index to about 93 to 99.8 so that the number average molecular weight of the polyurethane polymer to be produced is about 250,000 to 80,000.

On the other hand, a method of controlling the molecular weight using a monofunctional molecular weight controlling agent for isocyanate groups can also be applied to the present invention. Examples of molecular weight regulators include monools and monoamines. Particularly preferred are methanol, ethanol, t-butanol, other aliphatic monools, and monools such as 2,2,8.8-tetramethyl-4-hydroxypiperidine (hereinafter referred to as piperiditor). The molecular weight regulator is used to control the molecular weight by stopping chain elongation during formation of a polyurethane polymer, and the larger the amount used, the lower the molecular weight of the polymer will be produced. Therefore, by this method, about 2,
It can be adjusted to 50,000 to 80,000. However, with this method, it is generally difficult to obtain a polyurethane polymer with good physical properties compared to the method of adjusting the NGO index. Although a polymer with relatively good physical properties can be obtained by using piperiditul, the water resistance tends to be insufficient.

Therefore, in the present invention, as a method for adjusting the molecular weight of the polyurethane polymer to about 25,000 to 80,000, the above-mentioned N
The most preferred method is to obtain a polyurethane polymer by adjusting the GO index to about 93 to 99.8. That is, a high molecular weight diol (a) and a bifunctional extender (c) described below
The total number of functional groups of divalent isocyanate compound (b) is about 100, and the number of isocyanate groups is about 93 to 99.
8, and the three are reacted to obtain a molecular weight of approximately 2.
．． It is preferable to obtain a polyurethane polymer having a weight of 50,000 to 80,000.

Furthermore, in the present invention, a high molecular weight diol (a), a divalent isocyanate compound (b), and a difunctional extender (c)
is used as the main raw material, and the reaction is carried out at a weight ratio of (b+c)/(a+b+c) of about 0.15 to 0.5. More preferably, the weight ratio of (b+c)/(a+b+c) is about 0.2 to 0.
．． 45. The required performance of a hot melt adhesive for textiles is the flexibility of the adhesive, and especially when a hot melt adhesive is used in the form of a film, the texture of the bonded area is very important.

When the weight ratio of (b+c)/(a+b+c) exceeds about 0.5, the adhesive becomes hard, leaving a rough hard feeling in the bonded area and impairing the feel of the outer material. Therefore, (b+c)/
The smaller the weight ratio of (a+b+c), the better the flexibility of the hot melt adhesive. However, b+c)/(a+b+
When the weight ratio of c) is less than about 0.15, water resistance, solvent resistance, and mechanical properties deteriorate, causing problems. Therefore, the lower limit is about 0.15, particularly preferably about 0.2. More preferably, it is about 0.2 to 0.45.

As the polymer diol (a), a polymer diol containing polyoxytetramethylene diol as a main component is used. The use of polyoxytetramethylene-based diols results in more flexible polyurethane-based polymers compared to other high molecular weight diols (e.g., polyester-based diols), especially in the case of film-like hot melt adhesives for textiles. It is advantageous for In addition, compared to other high molecular weight diols, the resulting polyurethane polymer has high water resistance,
It has good washing durability especially when used for textiles. Therefore, the high molecular weight diol must be mainly composed of polyoxytetramethylene diol, especially at least about 60% by weight of the total high molecular weight diol.
, preferably about 80% by weight, is polyoxytetramethylene diol. In addition, polyoxytetramethylene diols include not only those whose molecular chain consists essentially of a polymer chain consisting only of oxytetramethylene groups, but also those having a copolymer state containing other oxyalkylene groups. Various high molecular weight diols having oxytetramethylene groups, such as polyester-based diols having polyoxytetramethylene groups (eg, caprolactone adducts of polyoxytetramethylene diol, etc.) may also be used. However, in these various polyoxytetramethylene diols, the content of oxytetramethylene groups is preferably at least about 80% by weight, particularly preferably at least about 80% by weight, for the reasons mentioned above.

Therefore, even if the high molecular weight diol (a) is a mixture of a polyoxytetramethylene diol and another high molecular weight diol, and/or even if the polyoxytetramethylene diol has a copolymer state, The total oxytetramethylene group content of high molecular weight diol (a) is at least about 80% by weight, preferably at least about 8% by weight.
Preferably it is 0% by weight. Most preferably, a polyoxytetra having substantially only a polyoxytetramethylene chain as a polyoxyalkyl chain (i.e., excluding residues of a low molecular weight dihydric alcohol or the like when used as an initiator) Methylene diols, ie, generally called polyoxytetramethylene gelcol, may be used alone or in combination with diols having different molecular weights.

As the molecular weight (average molecular weight in the case of a mixture of two or more types) of high molecular weight diol (a) decreases, flexibility decreases, so for this purpose, it is required to be about 500 or more, and more preferably about 500 or more. 600 or more is good. On the other hand, as the molecular weight increases, the durability against petroleum-based, chlorine-based, and other solvents tends to decrease, so taking into account dry-cleanability, the molecular weight of the high-molecular-weight diol (a) must be approximately 3,000 or less. The molecular weight of the polyoxytetramethylene diol, as well as the molecular weight of other high molecular weight diols that can be used in combination with it, is preferably within this molecular weight range. As the molecular weight diol, polyester diols such as polyether diols having oxyalkylene groups other than oxytetramethylene groups such as polyoxypropylene diols and poly(ε-caprolactone) diols can be used. However, in order to improve water resistance, it is necessary for these to not have too high a affinity for wood. Also, in polyoxytetramethylene copolymer diols,
It is preferable that the copolymerization component does not increase the parentness of the tree. For example, even if oxyethylene groups with high hydrophilicity are present, it is preferable to have fewer oxyethylene groups.

As the divalent isocyanate compound (b). Aromatic, aliphatic, alicyclic, and other diisocyanate compounds and modified products thereof may be used. For example, tolylene diisocyanate, diphenylmethane diisocyanate, naphthalene diisocyanate, p-phenylene diisocyanate,
Examples include xylylene diisocyanate, hexamethylene diisocyanate, methylene bis(cyclohexyl isocyanate), and hexahydrotolylene diisocyanate. These may be a mixture of isomers, or some or all of them may be modified products. However, modified products with a low content of isocyanate groups, that is, high molecular weight, are the above-mentioned (b◆c)/ However, the prepolymer produced from a portion of the high molecular weight diol (a) and the divalent isocyanate compound (b) is not a modified product as referred to herein. , respectively before the reaction (b*c)/(a+b
+c) shall be calculated.

The molecular weight of the modified product is not particularly limited, but is suitably about 800 or less. The preferred divalent isocyanate compound (b) is an aromatic diisocyanate such as diphenylmethane diisocyanate, with diphenylmethane diisocyanate being the most preferred.6 The difunctional chain extender (c) is a diol having a molecular weight of about 400 or less, preferably about 200 or less. and diamines are used. Diols are particularly preferred from the viewpoint of handling. Furthermore, in order not to reduce the water resistance of the resulting polyurethane polymer, it is preferable to use a hydrophobic bifunctional chain extender.

For example, chain extenders having a soxyethylene group such as ethylene glycol and diethylene glycol have relatively high hydrophilicity, and therefore, if used, it is preferable to use them together with other highly hydrophobic chain extenders. Examples of the difunctional chain extender include 1,4-butanediol, 1,6-
Hexanediol, other aliphatic hydrocarbon diols, etherified aliphatic hydrocarbon diols such as dipropylene glycol, aliphatic hydrocarbon diols such as cyclohexane dimetatool, aromatic compounds such as bisphenol A-propylene oxide adducts Examples include hydrocarbon diols, aliphatic diamines such as hexamethylene diamine and polyoxypropylene aminated at both ends, alicyclic diamines such as inphorone diamine, and aromatic diamines such as MOOA. Preferred are aliphatic diols having 4 to 10 carbon atoms, particularly 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, neopentyl glycol, and other aliphatic diols having 4 to 10 carbon atoms. Group hydrocarbon diols are preferred, and two or more of these divalent chain extenders may be used in combination.

The polyurethane-based polymer is obtained from the above-mentioned main raw materials, but other auxiliary raw materials such as catalysts, stabilizers, colorants, etc. may be used in some cases.

Suitable catalysts are organometallic compounds, especially organotin compounds and tertiary amines. As stabilizers, ultraviolet absorbers, light stabilizers, antioxidants, etc. may be used.

In the present invention, a polyurethane polymer is produced by a method such as a prepolymer method or a pseudo-prepolymer method using the above raw materials. It is preferred to employ a pseudo-prepolymer method in which the polymer is subsequently added to the prepolymer together with a difunctional chain extender. That is, high molecular weight diol (a)
A part of the divalent isocyanate compound (b) is reacted to produce a prepolymer having terminal isocyanate groups,
Next, this prepolymer and the remaining high molecular weight diol (a)
It is preferable to use a method of mixing and reacting the difunctional chain extender (c) with the resulting polyurethane polymer,
It can be used as is as a hot melt adhesive. Also,
It can also be used by forming into a film or the like. Further, among the above-mentioned auxiliary raw materials, stabilizers, colorants, and other additives can also be blended after the polyurethane polymer is formed. The hot melt adhesive of the present invention is made of the obtained polyurethane polymer alone or a polyurethane polymer mixed with a small amount of additives such as a stabilizer. In some cases, it can also be mixed with other polymer components (for example, polyurethane polymers, polyamide polymers, etc.) to form a mixed hot melt adhesive. However, the hot melt (JaZi) agent of the present invention can also have the above-mentioned polyurethane polymer as a main component. However, the Hommert adhesive of the present invention needs to contain the above polyurethane polymer as a main component, and preferably contains at least 60% by weight, preferably about 80% by weight of the above polyurethane polymer.

The hot melt adhesive of the present invention is particularly effective when used in the form of a film such as a tape, and the preferred method for forming the film is a melt film forming method. It is extruded into a film at a molding temperature of ~100°C. The thickness of this film is not particularly limited, but is suitably about 50 mm to 1 mm. The film may be embossed, but it is preferable not to stretch it actively.The film-like hot-melt adhesive thus obtained is sandwiched between, for example, woven or non-woven fabrics of the same or different types, and then heated using a hot roller, hot press, or iron. Adhesion is performed by heating and softening using a method such as glazing.

The hot melt adhesive of the present invention is specially designed to be used in the form of a film such as a tape, but the block can be melted as is and used in general hot melt applicators such as roll coaters and nozzles. It is also possible to apply it by use. It is also possible to powder it and use it for adhesion. Further, the hot melt adhesive of the present invention is particularly suitable as an adhesive for textiles as described above, but since it is an adhesive with relatively high mechanical properties,
It can also be used to bond base materials other than fibers, such as plastics, metals, ceramics, wood materials, etc., of the same or different base materials, or to bond these to fiber base materials. For example, metal sheets and foils such as aluminum, plastic sheets, films, and molded products such as polyester resin, vinyl chloride resin, and polyurethane resin,
It has high adhesion to surfaces coated with polyurethane paints and acrylic paints, as well as surfaces such as glass, ceramics, and wood. Can be used for adhesion between materials. Suitable fiber base materials include woven fabrics and nonwoven fabrics made of fibers such as nylon, polyester, acrylic, cotton, and other materials. It is particularly suitable for bonding fabrics for clothing made of fibers of these materials alone or in blends, or with fibers of other materials, and plastic films.

[Example] The present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples. In the Examples, "parts" means parts by weight unless otherwise specified. represent, also
“Hard content” is (b+c) of the main raw materials of polyurethane.
/(a+b+c) represents the weight ratio.

Example 1 After dehydrating 65 parts of polyoxytetramethylene glycol (hereinafter referred to as NG) having a molecular weight of approximately 2000 by heating and vacuum degassing, diphenylmethane diisocyanate (hereinafter referred to as M
Add 27.2 parts of DI (referred to as DI) and heat at 80°C under a nitrogen stream.
The mixture was stirred and reacted for 2 hours. A mixture of 035 parts of PTM having a molecular weight of about 2000 and 5.7 parts of 1.4-butanediol (hereinafter referred to as 1.4-BD), which had been mixed in advance, was added to this reaction mixture, and the mixture was rapidly stirred and mixed. At this time, the NGO index was 98 and the hard content was 25%. An exotherm was observed with the onset of the reaction and a substantially homogeneous mixture was obtained.

After about 5 minutes, this was poured into a drying container coated with a fluororesin and kept at 130° C. for 5 hours to obtain a polyurethane hot melt block made of a polyurethane polymer having a molecular weight of 42,000. This block was crushed into round pellets, and then extruded into a film with a thickness of 150 cm using a 40 mm diameter single screw extruder at an extrusion temperature of about 130 to 150°C. The tensile strength of the obtained film was approximately 210 kg/c++2. This film was slit into a tape with a width of 1 Cffi, sandwiched between two pieces of T/C broad (polyethylene terephthalate fabric/cotton cloth), and heated at 120°C, 140°C, and 16°C.
1kg/cm using a hot press heated to 0°C
When heated and pressed for 10 seconds at a pressure of 2, the peel strength of the adhesive part was 3.0, 3.5, and 3.7 kg/cm, respectively.
Met. The texture of the bonded area was not impaired at all, and there was no seepage from the woven fabric. In addition, the bonded cloth/C broad was tested for washing resistance and mineral turpentine solution under the conditions of detergent concentration 0.3z, bath ratio 1:50, time 10 minutes x 5 times, temperature 80°C.
The dry cleaning resistance was examined at 5°C for 10 minutes x 5 times, and the adhesive strength was maintained at 93% and 95%, respectively.

Example 2 After 85 parts of PTMo having a molecular weight of about 650 was dehydrated by heating and vacuum degassing, 54.7 parts of M[lI was added thereto, and the mixture was stirred and reacted at 80° C. for 2 hours under a nitrogen stream. 35 parts of PTMo having a molecular weight of about 650 and 1.4-
A mixed solution of 8.8 parts of BD was added, and the mixture was rapidly stirred and mixed. At this time, the NGO index was 98 and the hard content was 38%. Polyurethane was obtained in the same manner as in Example 1 (molecular weight: 41,000), and a film with a thickness of 200 l was made from it (tensile strength was 170 kg/cm2), and its adhesion to nylon cloth was examined. , 140℃
, the peel strength at teo°C is 3.3.3. ? , 3.
The weight was 7 kg/cm, and the texture of the bonded area was good. Furthermore, the adhesive strength after washing resistance test and dry cleaning test was maintained at 92% and 96%, respectively.

Example 3 After dehydrating 85 parts of PTMG with a molecular weight of 1000 by heating and vacuum degassing, 43.7 parts of MDI was added and the mixture was heated under a nitrogen stream for 85 parts.
The reaction was stirred at 0°C for 2 hours. 35 parts of PTMo having a molecular weight of about 1000 and 1.6-
A mixed solution of 10.1 parts of hexadiol was added and mixed quickly with stirring. At this time, the NGO index was 95 and the hard content was 35%. Polyurethane (molecular weight: 32,000) was obtained in the same manner as in Example 1 (molecular weight: 32,000).
00μ film (tensile strength is 80kg/cm2)
), when the adhesion to Tic broad was investigated, it was 1
Peel strength at 20'01140℃ is 3,8,40k respectively
g/c+a, and the texture of the bonded portion was good.

Further, the adhesive strength after washing resistance test and dry cleaning resistance test was maintained at 98% and 83%, respectively.

Comparative Example 1 After dehydrating 135 parts of PTMG with a molecular weight of 7,1 too many molecules by heating and vacuum degassing, 88.2 parts of MDI was added, and the mixture was stirred and reacted at 80° C. for 2 hours under a nitrogen stream. A premixed mixture of 35 parts of PTMG having a molecular weight of about 1000 and 24.8 parts of 1,4-BD was added to this reaction mixture, and the mixture was rapidly stirred and mixed. At this time, the NGO index was 95 and the hard content was 53%. Polyurethane (molecular weight: 34,000) was obtained in the same manner as in Example 1, and a film with a thickness of 150 mm was made from it (tensile strength was 170 kg/cm).
c+++2) When the adhesion to T/C broad was examined, a rough and hard feeling remained in the sealed area and the texture was poor.

Comparative Example 2 After dehydrating 85 parts of PTMG with a molecular weight of 1000 by heating and vacuum degassing, 45.1 parts of MDI was added and the mixture was heated under a nitrogen stream for 85 parts.
The reaction was stirred at 0°C for 2 hours. 35 parts of PTMo having a molecular weight of about 1000 and 1.4-
A mixed solution of 8.8 parts of BD was added, and the mixture was rapidly stirred and mixed. The NGO index at this time was 92. Hard content was 35%. Polyurethane (molecular weight 23,000) was obtained in the same manner as in Example 1, and a film with a thickness of 200μ was made from it (tensile strength was 25kg/cm2).
When examining the adhesion to Tic broad, it was found that 80℃, 1
Peel strength at 20℃ is 1.2 and 0.7 kg/cm, respectively.
It was low.

Example 4 The film produced in Example 1 was treated with PFT fi/l/
The adhesive force was examined by sandwiching the film between a nylon fabric and a urethane film/nylon fabric.

Peel strength 2.3-5.0k at 120-140℃
It exhibited high adhesion of g/am.

[Effects of the Invention] The hot melt adhesive of the present invention has an excellent texture at the adhesive part, and is also excellent in water resistance and solvent resistance (#dry cleanability), and is suitable for use with nylon, polyester, acrylic, Ideal as an adhesive for clothing fabrics made of cotton or its blends.

Claims (1)

[Scope of Claims] 1. High molecular weight diol (a) having a molecular weight of about 500 to 3000, whose main component is polyoxytetramethylene diol.
, a divalent isocyanate (b), and a difunctional chain extender (c) as main raw materials, and a weight ratio of (b+c)/(a+b+c+) of about 0.15 to 0.5, resulting in a molecular weight of about 2.
．． A hot melt adhesive whose main component is a substantially linear polyurethane polymer having a molecular weight of 50,000 to 80,000. 2. The hot melt adhesive according to claim 1, wherein the difunctional chain extender (c) is a diol having 4 to 10 carbon atoms. 3. High molecular weight diol (a) and bifunctional chain extender (c)
The total number of functional groups of divalent isocyanate compound (b) is about 100, and the number of isocyanate groups is about 93 to 99.
The adhesive according to claim 1, wherein the molecular weight of the polyurethane polymer is adjusted to about 25,000 to 80,000 by reacting the three components at a ratio of 8,000 to 80,000. 4. A polyurethane polymer is obtained by reacting a high molecular weight diol (a), a divalent isocyanate compound (b), and a bifunctional chain extender (c) by a pseudo-prepolymer method, Claim 1 adhesive. 5. The adhesive according to claim 1, wherein the hot melt adhesive is a hot melt adhesive formed into a film. 6. The adhesive according to claim 1, wherein the hot melt adhesive is a hot melt adhesive for fibers.