JP4865303B2 - Chloroprene rubber adhesive composition - Google Patents

Description

  The present invention relates to a chloroprene rubber adhesive composition. Specifically, the present invention relates to a chloroprene rubber adhesive composition used in the fields of vehicles, home appliances, architecture, and the like.

  A chloroprene rubber adhesive composition in which a thermoreactive phenolic resin and a basic metal oxide are added to chloroprene rubber is known to be industrially useful because of its excellent adhesiveness and heat resistance. (For example, see Patent Documents 1 and 2). Such excellent heat resistance is considered to be brought about by a complex of a methylol group, a dimethylene ether group, a phenolic hydroxyl group, and a basic metal oxide of a thermoreactive phenolic resin capable of forming a chelate. Yes. For this reason, at present, heat-reactive phenolic resins having many methylol groups, dimethylene ether groups and phenolic hydroxyl groups are used in chloroprene rubber adhesive compositions that require heat resistance.

  However, since the chloroprene rubber adhesive composition with higher heat resistance tends to have lower tackiness, such an adhesive composition has sufficient performance in low temperature environments such as applications that require initial adhesive strength or in winter. There is a problem that can not be demonstrated. Therefore, a heat-reactive alkylphenol resin having a low content of methylol group, dimethylol group or dimethylene ether group (for example, CKM-904 or CKM-919 manufactured by Showa Polymer Co., Ltd.) or a coumarone / indene resin, Although tackiness is improved by using a thermoplastic tackifying resin such as petroleum resin or polyterpene resin, a chloroprene rubber adhesive composition having both heat resistance and tackiness has not been developed yet.

On the other hand, due to the occurrence of “Six House Syndrome” and “Chemical Hypersensitivity”, the formaldehyde concentration in the room is severely restricted by the Building Standards Act revised in July 2003. Against this background, the development of environmentally friendly chloroprene rubber adhesive compositions such as low formaldehyde and non-formaldehyde is also an important issue.
The conventional chloroprene rubber adhesive composition containing the heat-reactive resol type phenol resin as described above has a problem that formaldehyde is gradually released from the heat-reactive resol type phenol resin. Therefore, at present, a resol type phenolic resin containing a formaldehyde catcher agent (for example, see Patent Document 3) is substituted, or a formaldehyde catcher agent is added to a chloroprene rubber adhesive composition. A chloroprene rubber adhesive composition that has only been reduced and does not release formaldehyde at all has not yet been developed.

Japanese Patent Publication No.46-40877 Japanese Patent Publication No.54-7820 JP 2001-164089 A

  Accordingly, the present invention has been made to solve the above-mentioned problems, and the object of the present invention is a chloroprene rubber that has both heat resistance and tackiness, is excellent in adhesiveness, and does not emit formaldehyde. It is to provide an adhesive composition.

Therefore, as a result of intensive studies to solve the conventional problems as described above, the present inventors have surprisingly found that a novolak type phenol obtained by reacting a phenol with an aldehyde in the presence of a specific catalyst. The inventors have conceived that it is effective to blend the resin with chloroprene rubber and an organic solvent, and have completed the present invention.
That is, the present invention relates to a chloroprene rubber adhesive composition containing chloroprene rubber, novolak-type phenol resin and an organic solvent, wherein the novolac-type phenol resin comprises phenols and aldehydes in the presence of a weak salt of a divalent metal. It can be obtained by reacting.
In this invention, it is preferable to contain 1-100 mass parts of said novolak-type phenol resins with respect to 100 mass parts of said chloroprene rubber. The novolac type phenolic resin preferably has a weight average molecular weight of 300 to 10,000.
In this invention, you may further contain 0.1-10 mass parts anti-aging agent with respect to 100 mass parts of said chloroprene rubber.
In this invention, it is preferable to further contain 0.1-30 mass parts at least one selected from the group which consists of a metal oxide, metal salts, and these mixtures with respect to 100 mass parts of said chloroprene rubber. The metal oxide is preferably MgO or ZnO, and the metal salt is preferably magnesium acetate or zinc acetate.
In this invention, it is preferable that solid content is 1-90 mass%.

  According to the present invention, it is possible to provide a chloroprene rubber adhesive composition that has both heat resistance and tackiness, is excellent in adhesiveness, and does not emit formaldehyde.

  The chloroprene rubber adhesive composition of the present invention comprises a novolac-type phenol resin obtained by reacting phenols and aldehydes in the presence of a weak salt of a divalent metal, chloroprene rubber, and an organic solvent. Yes. By blending such a specific novolac type phenolic resin in the chloroprene rubber adhesive composition, excellent heat resistance and adhesiveness can be imparted while improving tackiness. Furthermore, since this novolac type phenol resin does not contain free formaldehyde, the chloroprene rubber adhesive composition of the present invention also has a feature that it does not emit formaldehyde.

The novolak-type phenol resin in the present invention can be obtained by reacting phenols and aldehydes in the presence of a divalent metal weak acid salt as a catalyst.
The phenols may be those used for the production of general phenol resins, such as phenol, cresol, xylenol, butylphenol, octylphenol, nonylphenol, phenylphenol, cyclohexylphenol, naphthol, naphthalenediol, bisphenol A, Bisphenol F, bisphenol S, etc. can be used alone or in combination of two or more. Of these, alkylphenols such as butylphenol are preferably used from the viewpoint of compatibility with chloroprene rubber.

As the aldehyde, any aldehyde may be used as long as it is used in the production of a general phenol resin. For example, formaldehyde, paraformaldehyde, benzaldehyde, furfural and the like can be used alone or in combination of two or more.
Moreover, it is preferable that the compounding quantity of aldehydes is 0.1-2.0 mol with respect to 1 mol of phenols. When the blending amount of the phenol is less than 0.1 mol or more than 2.0 mol, it is not preferable because it becomes difficult to obtain a novolak type phenol resin having a desired weight average molecular weight.

The weak acid salt of the divalent metal as the catalyst may be a salt of a divalent metal such as Ca, Mg, Zn, Mn, Pb and a weak acid such as acetic acid, formic acid, boric acid, for example, zinc acetate, Examples thereof include magnesium acetate, manganese acetate, lead acetate, zinc formate, manganese formate, zinc borate, and manganese borate. These can be used alone or in combination of two or more.
Moreover, it is preferable that it is 0.1-80 mass parts with respect to 100 mass parts of phenols, and, as for the usage-amount of the weak acid salt of the bivalent metal which is a catalyst, it is more preferable that it is 1-50 mass parts. When the amount of the catalyst used is less than 0.1 parts by mass, it becomes difficult to obtain a novolac-type phenol resin having a desired weight average molecular weight, and when it exceeds 80 parts by mass, desired adhesive performance is obtained due to the influence of the residual catalyst. It is not preferable because it becomes difficult to be used.

The reaction between phenols and aldehydes may be a known method used for the production of general phenol resins. For example, phenols, aldehydes, and weak acid salts of divalent metals are charged all together, A method of reacting at a temperature, a method of charging a phenol and a weak salt of a divalent metal, adding an aldehyde at a predetermined temperature, and the like may be used. The reaction temperature at this time is preferably 50 ° C to 180 ° C, and more preferably 80 ° C to 150 ° C. If the reaction temperature is less than 50 ° C., the reaction rate is low and the reaction takes too much time, which is not preferable. If it exceeds 180 ° C., temperature control becomes difficult, which is not preferable. The reaction time is not particularly limited and may be appropriately adjusted according to the blending amount of each component, the reaction temperature, and the like.
The novolac-type phenol resin obtained by the above reaction may be further modified such as oil modification or rubber modification.

  The weight average molecular weight of the novolak-type phenol resin thus obtained is not particularly limited, but is preferably 300 to 10,000, and more preferably 300 to 8,000. When the weight average molecular weight is less than 300 or exceeds 10,000, it is difficult to obtain desired adhesive performance, which is not preferable.

  The content of the novolac type phenol resin in the chloroprene rubber adhesive composition of the present invention is preferably 1 to 100 parts by mass and more preferably 10 to 90 parts by mass with respect to 100 parts by mass of the chloroprene rubber. preferable. If the content is less than 1 part by mass or exceeds 100 parts by mass, it is difficult to obtain desired adhesive performance, which is not preferable.

The chloroprene rubber in the present invention is not particularly limited, and those obtained by polymerizing 2-chloro-1,3-butadiene (chloroprene) alone or those copolymerized with other monomers can be used. Here, the other monomer is not particularly limited as long as it is copolymerizable with 2-chloro-1,3-butadiene, and examples thereof include 2,3-dichloro-1,3-butadiene and the like. What is necessary is just to use it by 1-10 mass parts with respect to 100 mass parts 2-chloro- 1, 3- butadiene. The polymerization method may be a known polymerization method such as radical polymerization or ionic polymerization.
Furthermore, the chloroprene rubber in the present invention preferably has a hardness increase start time of 50 hours or less, and more preferably 25 hours or less. If the time required for starting the hardness increase exceeds 50 hours, it is difficult to obtain desired adhesive performance, which is not preferable. Here, the time required for starting the hardness increase refers to JIS in a low temperature thermostatic bath at -10 ° C. after putting a flat plate produced by pressing a chip of chloroprene rubber into an oven at 70 ° C. It means the time required for the hardness to rise by 10% or more from the value at the start of measurement when the change over time in the hardness of the flat plate is measured using an A hardness meter.
Such chloroprene rubber is already commercially available, and is called A type chloroprene rubber for adhesives, for example, Showprene AD and AC (registered trademark) manufactured by Showa Denko KK, and W type. Examples include chloroprene rubber for adhesive, such as Showprene W and WHV (registered trademark) manufactured by Showa Denko KK. Among these, from the viewpoint of heat resistance, showprene W and WHV (registered trademark) are preferable.

  The organic solvent in the present invention may be any organic solvent used in general chloroprene rubber adhesive compositions. For example, aromatic solvents such as toluene and xylene, methyl ethyl ketone (MEK), methyl isobutyl ketone (MIBK), Hexane, cyclohexane, 2-methyl-1-pentene, ethyl acetate, acetone, volatile oil for rubber and the like can be used alone or in combination of two or more.

The chloroprene rubber adhesive composition of the present invention may further contain an anti-aging agent, a metal oxide and a metal salt.
Antiaging agents include BHT (2,6-t-butyl-4-methylphenol), 2,6-di-t-butyl-4-ethylphenol, 2,2′-methylenebis (4-ethyl-6- Known phenolic antioxidants such as t-butylphenol) and 2,2′-methylenebis (4-methyl-6-t-butylphenol) may be used, and these may be used alone or in combination of two or more. it can.
Moreover, it is preferable that content of the antioxidant in the chloroprene rubber adhesive composition of this invention is 0.1-10 mass parts with respect to 100 mass parts of chloroprene rubber, and is 0.5-7 mass parts. More preferably. If the content is less than 0.1 parts by mass, it is difficult to obtain a desired anti-aging effect, and if it exceeds 10 parts by mass, it is difficult to obtain desired adhesive performance, which is not preferable.

Examples of the metal oxide include MgO and ZnO. Examples of the metal salts include magnesium acetate and zinc acetate. These metal oxides and metal salts can be used alone or in combination of two or more.
Moreover, it is preferable that content of the metal oxide and metal salt in the chloroprene rubber adhesive composition of this invention is 0.1-30 mass parts with respect to 100 mass parts of chloroprene rubber. If the content is less than 0.1 parts by mass, it is difficult to obtain desired heat resistance, and if it exceeds 30 parts by mass, it is difficult to obtain desired adhesive performance. Especially, when it contains MgO independently, it is preferable to contain 0.1-20 mass parts of MgO with respect to 100 mass parts of chloroprene rubber. Moreover, when containing ZnO and / or metal salts, it is preferable to contain 1-30 mass parts of ZnO and / or metal salts with respect to 100 mass parts of chloroprene rubber, and 1-20 mass parts is contained. More preferred.

The method for preparing the chloroprene rubber adhesive composition of the present invention is not particularly limited, and a general method for preparing a chloroprene rubber adhesive composition may be used. Such preparation methods include, for example, a method of directly dissolving chloroprene rubber, novolak-type phenol resin, anti-aging agent, metal oxide, metal salt, etc. in an organic solvent, chloroprene rubber, aging as necessary Examples thereof include a method in which an inhibitor, a metal oxide, a metal salt, and the like are uniformly mixed with a roll machine and then dissolved in an organic solvent together with a novolac type phenol resin.
The solid component content of the chloroprene rubber adhesive composition thus obtained can be prepared according to the desired application, but is preferably 1 to 90% by mass, and 10 to 50% by mass. More preferably it is. If the solid component content is less than 1% by mass, it is difficult to obtain desired adhesive performance, which is not preferable. If it exceeds 90% by mass, desired workability is hardly obtained when using the adhesive composition. This is not preferable.

EXAMPLES The present invention will be described below in more detail with reference to examples, but the present invention is not limited to the examples.
Characteristic evaluation of the chloroprene rubber adhesive compositions obtained in Examples and Comparative Examples was performed by the following measurements.
(1) adhesion, the evaluation of the evaluation adhesion and heat resistance of the heat resistance and tackiness was carried out in accordance with the T-peel strength test of JIS _{K-6854 -1994.}
(1-1) Adhesiveness The chloroprene rubber adhesive composition was applied to a 25 × 75 mm area of 25 × 150 mm No. 11 canvas using a brush with 0.03 g / cm ² and left at room temperature for 1 hour. After repeating this operation three times, let stand at room temperature for 20 minutes, stick two by two, press with a 5kg hand roll one way five times, and cure in a constant temperature and humidity chamber (25 ° C, humidity 60%) for one week. A test specimen for measurement was prepared. Thereafter, T-type peel adhesion strength was measured at a rate of 200 mm / min in a 25 ° C. atmosphere using Tensilon. In addition, the measurement was performed 5 times and the average value was made into the peeling strength in 25 degreeC atmosphere. It means that the higher the peel strength in the 25 ° C. atmosphere, the better the adhesiveness.
(1-2) Heat resistance The same test specimen for measurement as that used in the evaluation of adhesiveness was allowed to stand for 20 minutes in an 80 ° C atmosphere, and then T-type peel adhesion strength at a rate of 200 mm / min in an 80 ° C atmosphere. Was measured. In addition, the measurement was performed 5 times and the average value was made into the peeling strength in 80 degreeC atmosphere. The higher the peel strength in an 80 ° C. atmosphere, the better the heat resistance.
(1-3) Tackiness A chloroprene rubber adhesive composition is applied to the surface of a glass plate and kraft paper at a thickness of 250 μm, placed in a constant temperature and humidity chamber (25 ° C., humidity 60%), and every 10 minutes. The kraft paper was bonded to the glass plate, and the time until no longer adhered was measured as the tack time. A longer tack time means better tackiness.

(2) Formaldehyde emission rate evaluation The formaldehyde emission rate test is performed in accordance with JIS A- _1901-2003 "Measurement method for emission of volatile organic compounds (VOC), formaldehyde and other carbonyl compounds in building materials-Small chamber method". It was.

Synthesis examples of the novolac type phenol resins (resins A to D) in the present invention are shown below.
(Synthesis of Resin A)
A mixture of 50.0 parts by mass of pTBP (p-tert-butylphenol), 50.0 parts by mass of phenol, 50.0 parts by mass of a 37.0% by weight formalin aqueous solution and 5.0 parts by mass of zinc acetate was added to a stirrer and A four-necked flask equipped with a thermometer was charged and reacted at 100 ° C. for 3 hours. Then, it dehydrated under reduced pressure at 160 ° C. to obtain 112.4 parts by mass of a novolac type phenolic resin (resin A) having a weight average molecular weight of 2100.

(Synthesis of Resin B)
pTBP 50.0 parts by mass, phenol 50.0 parts by mass, 37.0% by mass of formalin aqueous solution 70.0 parts by mass and zinc acetate 5.0 parts by mass, a four-neck equipped with a stirrer and a thermometer The flask was charged and reacted at 100 ° C. for 3 hours. Then, it dehydrated under reduced pressure at 160 ° C. to obtain 120.9 parts by mass of a novolac type phenolic resin (resin B) having a weight average molecular weight of 5100.

(Synthesis of Resin C)
Four mixtures comprising 50.0 parts by mass of pTBP, 50.0 parts by mass of phenol, 70.0 parts by mass of a 37.0% by weight formalin aqueous solution and 5.0 parts by mass of magnesium acetate, equipped with a stirrer and a thermometer. The flask was charged and reacted at 100 ° C. for 3 hours. Then, it dehydrated under reduced pressure at 160 ° C. to obtain 119.8 parts by mass of a novolac type phenol resin (resin C) having a weight average molecular weight of 5000.

(Synthesis of Resin D)
A mixture consisting of 50.0 parts by mass of pTBP, 50.0 parts by mass of 3,5-xylenol, 50.0 parts by mass of a formalin aqueous solution of 37.0% by mass and 5.0 parts by mass of zinc acetate was added to a stirrer and a thermometer. The prepared four-necked flask was charged and reacted at 100 ° C. for 3 hours. Then, it dehydrated under reduced pressure at 160 ° C. to obtain 113.3 parts by mass of a novolac type phenol resin (resin D) having a weight average molecular weight of 3020.

As a comparative example, a synthesis example of a novolac type phenol resin (resins E and F) and a resol type phenol resin (resin G) is shown below.
(Synthesis of Resin E)
pTBP 50.0 parts by mass, phenol 50.0 parts by mass, 37.0 mass% formalin aqueous solution 50.0 parts by mass and oxalic acid 2.0 parts by mass, a four-neck equipped with a stirrer and thermometer The flask was charged and reacted at 100 ° C. for 3 hours. Then, it dehydrated under reduced pressure at 160 ° C. to obtain 118.5 parts by mass of a novolac type phenol resin (resin E) having a weight average molecular weight of 2100.
(Synthesis of Resin F)
pTBP 50.0 parts by mass, phenol 50.0 parts by mass, 37.0 mass% formalin aqueous solution 70.0 parts by mass and oxalic acid 3.0 parts by mass, a four-neck equipped with a stirrer and thermometer The flask was charged and reacted at 100 ° C. for 3 hours. Thereafter, dehydration was performed at 160 ° C. under reduced pressure to obtain 125.9 parts by mass of a novolac type phenolic resin (resin E) having a weight average molecular weight of 5100.

(Synthesis of Resin G)
pTBP 100.0 parts by weight, 37.0% by weight formalin aqueous solution 170.0 parts by weight and 10.0% by weight caustic soda aqueous solution 5.0 parts by weight, a four-neck equipped with a stirrer and thermometer The flask was charged and reacted at 100 ° C. for 2 hours. After completion of the reaction, 100.0 parts by mass of toluene and 1.0 part by mass of 10.0% sulfuric acid aqueous solution were added to neutralize, and then allowed to stand to remove the lower layer water. 100.0 parts by mass of water was further added, mixed and allowed to stand again, and the lower layer water was removed as before. Then, it dehydrated under reduced pressure at 100 ° C. to obtain 125.9 parts by mass of a resol type phenolic resin (resin G) having a weight average molecular weight of 2280.
Table 1 shows the composition of the novolac type phenol resins (resins A to F) and the resol type phenol resin (resin G).

Next, preparation examples of the chloroprene rubber adhesive composition of the present invention are shown below.
[Example 1]
50.0 parts by mass of the resin A was dissolved in 50.0 parts by mass of MEK to obtain 100.0 parts by mass of a resin solution 1 containing 50.0% by mass of the resin.
Chloroprene rubber 100.0 parts by mass (Showa Denko Co., Ltd., Shopreen WHV) and BHT (Ouchi Shinsei Chemical Co., Ltd., Nocrack 200) 2.0 parts by mass with a two-roll mill at 60 ° C. or less for 20 minutes This was dissolved in a mixed solution consisting of 100.0 parts by mass of MEK, 150.0 parts by mass of ethyl acetate and 150.0 parts by mass of cyclohexane to obtain rubber solution 2.
The resin solution 1 and the rubber solution 2 were uniformly mixed with a stirrer to obtain 602.0 parts by mass of a chloroprene rubber adhesive composition. The solid content of the chloroprene rubber adhesive composition was 25.2% by mass.

[Examples 2 to 9]
In the same manner as in Example 1, each resin solution 1 and rubber solution 2 were prepared according to the formulation shown in Table 2, and chloroprene rubber adhesive compositions of Examples 2 to 9 were obtained.

[Comparative Example 1]
50.0 parts by mass of the resin E was dissolved in 50.0 parts by mass of MEK to obtain 100.0 parts by mass of a resin solution 1 containing 50.0% by mass of the resin.
Chloroprene rubber 100.0 parts by mass (Showa Denko Co., Ltd., Showrene WHV), BHT 2.0 parts by mass, MgO 4.0 parts by mass (Kyowa Chemical Industry Co., Ltd., Kyowa Mag 150) and ZnO 5.0 parts by mass Kneading is carried out for 20 minutes at 60 ° C. or less with a two-roll mill, and this is dissolved in a mixed solution consisting of 100.0 parts by mass of MEK, 150.0 parts by mass of ethyl acetate, and 150.0 parts by mass of cyclohexane, and rubber solution 2 Got.
The resin solution 1 and the rubber solution 2 were uniformly mixed with a stirrer to obtain 611.0 parts by mass of a chloroprene rubber adhesive composition. The solid content of the chloroprene rubber adhesive composition was 26.4% by mass.

[Comparative Example 2]
In the comparative example 1, except having used the resin F, operation similar to the comparative example 1 was performed, and 611.0 mass parts of chloroprene rubber adhesive compositions were obtained. The solid content of the chloroprene rubber adhesive composition was 26.4% by mass.

[Comparative Example 3]
In a reactor equipped with a stirrer and a thermometer, 50.0 parts by mass of the resin G and 50.0 parts by mass of toluene were charged, and the internal temperature was raised to 50 ° C. and dissolved. Thereafter, MgO (Kyowa Chemical Industry Co., Ltd., Kyowamag 150) 3.5 parts by mass and water 0.5 parts by mass were added, and the chelation reaction of the resol type phenol resin (resin solution) was carried out as it was for 5 hours. 1) 104.0 mass parts was obtained.
The rubber solution 2 was obtained in the same manner as in Comparative Example 1.
100 parts by mass of the resin solution 1 and the rubber solution 2 were uniformly mixed with a stirrer to obtain 611.0 parts by mass of a chloroprene rubber adhesive composition. The solid content of the chloroprene rubber adhesive composition was 26.7% by mass.
In the chloroprene rubber adhesive compositions of Examples 1 to 9 and Comparative Examples 1 to 3, the contents of each component and property evaluation are shown in Table 2.

  As shown in Table 2, the chloroprene rubber adhesive compositions of Examples 1 to 9 have adhesiveness and heat resistance comparable to the chloroprene rubber adhesive compositions of Comparative Examples 1 and 2, and Excellent in properties. Further, the chloroprene rubber adhesive compositions of Examples 1 to 9 are improved in tackiness and heat resistance even when compared with the chloroprene rubber adhesive composition using the resol type phenol resin for long tack of Comparative Example 3. In addition, it does not dissipate formaldehyde.

Claims (8)

In the chloroprene rubber adhesive composition containing chloroprene rubber, novolac-type phenolic resin and organic solvent,
A chloroprene rubber adhesive composition, wherein the novolac type phenol resin is obtained by reacting phenols and aldehydes in the presence of a weak acid salt of a divalent metal.   The chloroprene rubber adhesive composition according to claim 1, wherein the chloroprene rubber adhesive composition contains 1 to 100 parts by mass of the novolac type phenol resin with respect to 100 parts by mass of the chloroprene rubber.   The chloroprene rubber adhesive composition according to claim 1 or 2, wherein the novolac type phenolic resin has a weight average molecular weight of 300 to 10,000.   The chloroprene rubber adhesive composition according to any one of claims 1 to 3, further comprising 0.1 to 10 parts by mass of an anti-aging agent with respect to 100 parts by mass of the chloroprene rubber. Relative to the chloroprene rubber 100 parts by weight, metal oxide, claims 1 to 4, characterized in that it contains at least one of 0.1 to 30 parts by weight further selected from the group consisting of metal Shio及 beauty mixtures thereof The chloroprene rubber adhesive composition according to any one of the above.   The chloroprene rubber adhesive composition according to claim 5, wherein the metal oxide is MgO or ZnO. 6. The chloroprene rubber adhesive composition according to claim 5, wherein the metal salt is magnesium acetate or zinc acetate.   Solid content is 1-90 mass%, The chloroprene rubber adhesive composition as described in any one of Claims 1-7 characterized by the above-mentioned.